Topic: kvm switch hell: please advise :)

[devnullius]

(English translation is here ;p...)

Emulated DDC usually works just fine. BUT is based on an internal table, which might not suffice under certain conditions. Non-Ghost KVM models cannot update the table in those circumstances.

USB emulation for BlackBox ServSwitch models come in two types:
- emulated (default HID USB devices only), supports hotkey. CPUs will have always-on connection to KB/M (no lags when switching).
- transparant, no hotkey support! Only focussed CPU is connected, so lag is expected when switching (device needs to be hot-plugged again).

MODELS with emulated HID-only:
* KV9614A (Emultated DDC). 4x USB HID devices supported. VGA.
 
MODELS with transparant USB:
* KV9604A (Emultated DDC). 4x DVI-D.

MODELS with DVI-D DDC Ghost:
* ACS2100A
OFFICIAL SITE: http://www.blackbox.nl/nl-nl/fi/1449/12272/DVI-D-DDC-Ghost-Emulator/?ac=acs20

MODELS with ALL FEATURES:
* KV2004A:
OFFICIAL SITE: http://www.blackbox.nl/nl-nl/si/12446/ServSwitch-Wizard-DVI-DL-USB-Multivideo/S1.O3/kv2004a
Emulated USB ++ Transparant USB ++ Ghost (update table with DDC/EDID of troublesome screen). Comes in single-head to quad-head dual-link types (KV2004A, dual KV2204A, triple KV2304A, KV2404A). Prices: €495/913/1220/1527). 

<--- END OF RE-WRITTEN TRANSLATION

Thank you BlackBox support: this is the first in-depth answer I received at this time! Kudos ;p

IN SHORT: my list can be re-written to only contain the KV2204A (+maybe KV2004A depending on the competition).... that helps BIG time!

Karma...

devnullius

[devnullius]

I again got good customer support, transcripts below!

ME: Sent: Sunday, February 24, 2013 12:51 PM
To: info@highseclabs.com
Subject: High Sec Labs General Inquiry Form - Price Request

 
Looking for DisplayPort 1.2 KVM Switches, yours is one of the few that offers it. But... No links to buy, nothing on price. Which probably means it is Crazy expensive? Or not to market yet? Please inform! Also, is it DualMode (= DisplayPort++)? And more info on USB... Is it truly transparant? I suppose so, but... And this device is multi-headed too? Love to hear from you guys... :)

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ZOHAR VERED @ HSL: Our devices are secure KVM switches. This means that it is EAL 4+ certified and not exactly competing against standard KVM switches. The USB that will be mapped is only for mouse, keyboard and SC reader nothing else.

Here are the prices:
K504 - 4-Port High Security DisplayPort KVM Switch, USB PS/2 keyboard and mouse, DisplayPort video, Active anti-tampering, Front panel push-buttons, CPN06442 $660
K504E - 4-Port High Security DisplayPort KVM Switch, USB PS/2 keyboard and mouse, DisplayPort video, Audio out, USB user authentication port, Active anti-tampering, Front panel push-buttons, CPN06445 $700
K524E - 4-Port Dual-head High Security DisplayPort KVM Switch, USB PS/2 keyboard and mouse, 2 x DisplayPort video, Audio out, USB user authentication port, Active anti-tampering, Front panel push-buttons, CPN06448 $990
 
----

ME: You are right, security sec is not what I am looking for, but I do see advantage in total seperation of hardware / data.

Also, you offer DisplayPort v1.2, which not many do.

I am looking for dual head & dual mode. Do you support dual mode? Eg. can I easily use a passive converter to use the switch for DVI/HDMI/VGA CPUs? Also known as DisplayPort++? Terminology is vague / confusing :)

Price might be a little over budget, but I am willing to go the extra buck. Which brings me to my last question: how do you handle complex USB mice & keyboards? This is a big problem for many (older) KVM switches. Does our security features solve this for me?

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ZOHAR VERED @ HSL: Dual mode is not supported (I don’t think it will be supported with 1.2 at all). All the passive convertors will not work between the KVM and the monitor.
There are two ways to handle USB.
1.       The mouse and keyboard ports will handle only mouse and keyboard. All mouse and keyboards should work but if it is sending a macro or any other commands which are not keyboards related it will be blocked (such as a Bloomberg keyboard for example).
2.       We have a DPP (dedicated Peripheral Port) port on the device which can be used for any peripheral. Usually we limit the use for SC readers or any other device requested by the customer but we can open it completely (remove all restriction) which will allow any USB device to be connected.

To switch between channels you can either use hotkeys, via push buttons or use RDC.
What we can do, is for you to purchase a switch and I will allow you to return it if you are not happy. The best way to purchase is via Norway but I have a partner in NL as well.
If you will purchase from Norway and are not requiring a secure device I can also discount the product a bit. (EDIT: that's service! :>)

----

ME: 2 (smaller) questions that pop to my mind (a next reply will no doubt have more questions:)...
- no dual mode, and won't be implemented (probably). Is this because of some technical impossibility I did not think of yet? Or is it just not important for your current KVM Switch's product branch?
And does this also mean I can only use Digital Links? I might still be lacking technical know-how on this topic... Your patience truly is appreciated!
- USB... Again, a tough topic! Do you mean to say that only keyboards & mouses that are fully USB HID compliant are allowed? Or are complex keyboards and mice supported too? Eg., is it truly transparant USB? And if non-HID KB/M's are used, will they still support hotkey??

:) Till my next question & peace!

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ZOHAR VERED @ HSL:
1.       The answer is both. In DP 1.2 the frequency does not seem to match passive convertors. Also for security we did not explore this avenue.

2.       Through the DPP is 100% truly transparent. Through the mouse and keyboard ports its only HID complaint. I must say that I did not get many that did not work. If you send me a link to your keyboard I will tell if it will work on not through the keyboard port.

----

RESEARCH (c.) by Devnullius ('013) - OR how passive conversion fails for DP 1.2 :/

I Googled for:
dp 1.2 passive converter
and
produce displayport 1.2 signal from (hdmi OR dvi)

And found: STMicroelectronics  STDP2690 high-speed DisplayPort to DisplayPort dual mode converter
http://www.st.com/st-web-ui/static/active/en/resource/technical/document/data_brief/DM00056675.pdf

NO current resellers found - I contacted a distributor that is going to look into it... But later I also found this: http://www.eetindia.co.in/ART_8800669050_1800004_NP_eeb8d286.HTM (ST's Mystique family products: A/V converters bridge HDMI, DisplayPort). ST seems to be the only one trying to tackle this problem. Also see first "*Research link" at the bottom of the page (chipset manufacturer).

Copy Paste from the manual:
This device includes a VESA DP Standard Ver. 1.2 compliant receiver and transmitter, implementing single link DisplayPort input and output ports comprising four Main lanes, AUX CH, and HPD.
The STDP2690 uses ST's latest generation DisplayPort dual mode transmitter technology that supports both DisplayPort and TMDS signal formats (DP++).
DisplayPort receiver and transmitter support HBR2 speed, a data rate of 5.4 Gbps per lane with a total bandwidth of 21.6 Gbps link rate.
In addition, the transmitter is capable of supporting HDMI or single link DVI output through a passive level translator (dongle).
When configured as HDMI output, this device supports link rate up to 2.97 Gbps that corresponds to a pixel rate of 297 MHz, quite adequate for handling video timings up to FHD 120 Hz 3D formats.
This device delivers deep color video up to 16-bits per color at 1080p 60 Hz and lower video resolutions.
The STDP2690 allows audio transport from the source to desired audio rendering devices over the DP++ output or through the SPDIF port. The audio signal from the source can be routed simultaneously to DP++ and SPDIF output ports. For example, the STDP2690 allows routing of any two audio channels on the SPDIF port, while transporting up to eight channels on the DP++ port.
The STDP2690 supports RGB and YCbCr colorimetric formats with color depth of 16, 12, 10, and 8 bits.
This device features HDCP 1.3 content protection scheme with an embedded key option for secure transmission of digital audio-video content. It also operates as an HDCP repeater for the downstream sink.
The AUX-to-I2C translator in the STDP2690 allows the upstream DisplayPort source to access EDID and transfer MCCS commands to a downstream sink over the HDMI interface when used with a level translator.
The device has an on-chip microcontroller with SPI and I2C host interface for system configuration purposes. STDP2690 can be configured with an external SPI Flash for custom applications or simply configured from an external host controller through I2C interface. (END COPY PASTE)

ALSO note from: http://www.displayport.org/faq/
  Q: I just purchased a monitor that only has a DisplayPort connection. How can I hook this up to my computer that only has VGA, DVI or HDMI?
  A: There is not a cost effective way to do this. The adaptors that are available only work from a DP computer to a VGA, DVI or HDMI monitor and not the other way around.

In general, searching for DisplayPort 1.2 KVM Switches is hard... Try this (exact) google search to see for yourself: --->
((dp OR displayport OR "display port" OR display-port) AND +(1.2 OR v1.2)) "kvm switch" multi-mode <---

Abstracting this information... I'd say it (=dual-mode DP 1.2) could be done, technical, but at a high cost.

Question that remains for me is: what KIND of signal does DisplayPort v1.2 offer?? I should research that further before nagging support again ;)

Some research links:
* DP hub/splitter? http://superuser.com/questions/230744/looking-for-a-real-displayport-hub-splitter
* STMicroelectronics (ST.com) Mystique DisplayPort 1.2 converter (DVI/VGA/HDMI)
https://encrypted.google.com/search?aq=f&oq=STmicroelectronics+mystique+(%E2%82%AC+OR+%24)&q=STmicroelectronics+mystique+(%E2%82%AC+OR+%24) . As far as I can tell, it was released June 2012 and then went DEAD :(
* http://www.displayport.org/faq/
* "Full HD 3D" & DisplayPort 1.2? http://www.avsforum.com/t/1336045/full-hd-3d-displayport-1-2

CONCLUSIONS:
- I would love this device. Industrial quality (me always likes that), DP v1.2.
- USB probably will be stable. Manufacturer will check when needed, but he hardly ever experienced any problems. Tweaks are available (less security=lower cost, opening USB for specific hardware or everything - done at reseller's(?)).
- According to information I found I could attach a HDMI-screen to a CPU with DP port without problems. But NOT a DP monitor to a HDMI CPU. What does this mean for me, with this KVM Switch?
This KVM Switch comes with DP "CPU"? I should check this logic with support!
So to DP CPU I could attach my old screens? But I do not attach a screen, I attach a real computer. That computer is the OUT-port. From that a cable starts (HDMI/DVI) ending in... DP KVMS. DP KVMS would be the "screen" in this logic, and therefore must originate in DP too. Which it didn't, it started with HDMI at the CPU computer...
ERGO ==> This KVM Switch with Display Port version 1.2 can only support CPUs with Display Port 1.2 and therefore is not a good solution to me (I need allround compatibility!).
BUT I am really fixated at Display Port v1.2 technology (bandwith! future compatibility). So if I MUST buy this device I must also buy a device that will transform "classic" HDMI/DVI/VGA to DP. There is not passive conversion possible. So this device would be expensive and COULD make mistakes... Currently, only st.com seems to have the technology (chipset) to do this. Very few product lines actually use this chipset and those that do are kinda invisible in Real Life :s - support request is outstanding...
FOR NOW I cannot advise this device... Still I'm open to buy extra hardware, if only it was available (and reasonably priced would be nice too! less that 100$? 200$ greatly appreciated;p).

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ZOHAR: In general it’s OK. I think the Blackbox product is a none secure product as far as I know.

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Karma...

devnullius!

[Samker]

WOW, this is what I call REAL research! 


P.S.

@Samker... Good! You can learn something new ;p

...

Confirmed!

[sales@adder.com]

Devnullius,

I have sent this posting along with some file attachments to the email address you supplied via our website. Our account manager in Holland has replied to your first mail. Possibly the e-mail address you set up is not receiving mail as it should do?


You have asked on your forum a number of very interesting questions. In short there is no quick answer to many of them and almost no single product that will provide all of the things you want in a simple, easy to swallow solution. If only the work were that simple!


So where do we start... Digital Video? I have attached a quick tutorial that explains the main differences between the most common video standards. To understand how different switch and extension vendors approach a solution, one first needs to understand how the these standards applied.  I would particularly draw your attention to the conversion matrix. As you will see, not all standards work with each other. ( your question can I easily use VGA to DVI/HDMI converters? VGA <-> DVI should not be a problem? Yes it is!) Then we need to look a little more closely at USB and how that may be re-enumerated and each switch generically emulated or a 3rd approach. The USB emulation document provides some information to you on this.

 

In this case, it is a question of understanding the technology in order to understand how a solution maybe delivered. There is simply no panacea to the apparently simple requirement of have an extended USB keyboard, a full speed emulated gaming mouse, 4 different computers all with different video cards providing various levels of support of their own standard connected via a switch to a single monitor which may conform to one but not all of the standards. The expectation is the the Switch should simply "do" everything... After all, it's just a switch right?  Here at Adder we have spent decades of man years developing the most advanced and configurable solutions in order to overcome the majority of issues. I would urge you to read and digest the large amount  of information contained in the manuals and data sheets in order to understand your own requirement and thus the most suitable product for you and you own particular application.

 

A typical example may be: The user expectation is for a DisplayPort switching system to provide an immediate picture to the connected monitor upon each switch. To emulate ALL of the potential DP variants makes such a switch commercially unviable. Therefore the majority of the available switches (Including ours) with disconnect and re-connect a DP signal. This takes a second or two depending upon the individual monitors and video cards being used. This may or may not be practical to the User. DVI on the other hand can be emulated to the computers video card efficiently and at a relatively low cost making the switching significantly faster. If the user is operating at a level of Dual Link DVI or lower, then there is no requirement to move to DP. (and don't get me started on DP++ or HDCP or DPCP!)

 

Moving onto Secure switches, we enter into a totally different environment altogether. Adder manufacture a range of Secure switches, to EAL4+ and EAL2+ Common Criteria standards. We also have switches which add Tempest Qualified Design to this standard. Again, one needs to look rather more deeply than  few lines on a forum can provide. CCC is a commercial standard, in essence qualifying that the components, design, warehousing and distribution and managed in an approved fashion. It does not however provide anything in the way of, for example, security between the ports. This is what Tempest qualification provides. So for a secure switch, I can leave you to draw your own conclusions as to what is worth investing in and again what the requirements are.

 

Here are some other links you may find useful

 

Page 12 provides information on configuring Hybrid DDC http://www.adder.com/sites/default/files/pdf/manuals/AV4PRO-DVI%20v1-1b.pdf

Secure Analogue and Digital KVM Switches http://www.highseclabs.com/Resources/Black-Box%20t265_st.pdf

 

Best of luck with your forum, you certainly have your work cut out!

 

 

[devnullius]

Best of luck with Samker's SCF-forum, you certainly have your work cut out!

Sigh... Here I am, hoping I was finalizing the list... :s

Anyways - spoken about excellent customer support - even registering to a forum just to reply and get this information out... What can I say, I'm touched?

< - _ K a r m a _ - >

        devnullius

[devnullius]

I indeed got a reply from Adder Support earlier this week. It addressed 1 specific question I had... I withheld it from you, I'll make up for it now.

Dear Sir*

Many thanks for your enquiry, and I apologise that I could not respond last Friday, but I was abroad for business and had no chance to have internet access.

The Command and Control switch is a switch just for keyboard and mouse. So in a way it is a classical KVM switch minus the video connection. The monitors stay directly connected to the PC, and then the keyboard and mouse connections from each PC are connected to this switch. You can change channels in several ways, via hotkeys, or with use of the Freeflow software, by moving the mouse from 1 Monitor to the next.

The switch is often used in combination with the AdderLink Infinity, which are IP based transmitters and receivers, and enables you to create a kvm matrix. So many servers and several users stations.

Unfortunately, you did not leave me a telephone number so I could not contact you by phone to ascertain what you were looking for and where to puchase it.

I am at the office today, so if you would like further advice, please do contact me.

Our distributor in the Netherlands is Intronics, tel 0342 407040.

Kind regards


Bettina Berk

Sales Manager West & Southern Europe
ADDER Technology
Crown Business Studios
Amsterdam Office
Web: www.adder.com

So... Karma!

devnullius
   


*Miss, pretty please ;p

[devnullius]

just to give some examples...

USB...

I have this PS/2 KVM switch. More about that once I have a new one. For now I just thought to post some mice brands & types that failed on my PS2 Switch. All ice are connected through regular passive converters to usb.

The mice themselves are connected through a USB extension cable (2 meters).

I always used the Logitech Optical Mouse M-BT96a. It seems to work just fine BUT it causes errors with the Keyboard (all PS/2 to the KVM but from KVM to CPU it is USB passive conversion again). KB errors are that a key gets pressed many times (mostly the number "4"). Backspacing or Deleting makes it worst. KB might only disturb depending on 1. which other USB devices are connected, in which order and 2. which USB port is used. Also mobo-ports vs PCI-USB card ports make a difference. (Un)plugging in a specific mysterious order is important too. I finally figured this out and replaced the mouse.

Mice tested to replace my old one:
- Fujitsu Siemens Logitech M-UAE96 USB Mouse. Not detected. Power works.
- HP M-UAE96 USB Mouse. Not detected. Power works. Probably Logitech.
- Dell M-UAR DEL7 USB Mouse. Not detected. Power works. Logitech?
- Logitech M-RBH113 USB Mouse. Not detected. Power works. Wireless mouse - what was I thinking! ; )
- HP M-SBF96 PS/2 Mouse. Connected to USB extension cable with passive PS/2 to USB converter (yes, they exist too... dx.com!)
- Logitech MouseMan+ M-CW47 (patent pending). Old ergonomical PS/2 mouse, with track-ball. Recognized instantly, and any keyboard problems (repeated keystrokes) are solved by re-connecting. BUT this mouse is just too old and works on my nerves with the bad working pointer-ball thingie ;p
- Logitech Optical Mouse M-BT96a

Karma,

devnullius

[devnullius]

(English translation, here: http://scforum.info/index.php/topic,8018.msg20291.html#msg20291)


This is Dutch copy-paste!

----- 23 feb., '13.

devnullius:
Als de muispoort mouse emulation UIT staat, hoe wordt dan contact gehouden met de CPUs? Indien u meldt dat multifunctionele muizen dan gewoon werken, verbaast het me weer dat een draadloos toetsenbord (met usb dongle) dan niet werkt... Want dat doet vermoeden dat sommige andere complexe muizen/toetsenborden stiekem ook problemen gaan geven?

En als mouse emulation uit staat - kan ik dan nog wel gewoon hotkey combo gebruiken? Idem, maar dan met toetsenbord aangesloten op USB hub?

Mbt EDID... Kunt u toch nog iets meer vertellen over de gebruikte technieken? Ik zie allerlei kreten voorbij komen, maar DDC is beter dan DDC2 is beter dan DDC2B(i)...? Heeft u volledige DDC ondersteuning.

Nog een vraag mbt EDID: ik begrijp dat de CPUs geen constant-on connectie hebben met de switch? Dus dat slechts 1 CPU op ieder moment een actieve monitorverbinding heeft (denkt te hebben).

Mogelijk heb ik later nog vragen, ik ben echt al lang aan het studeren op dit onderwerp

Dank voor uw genomen moeite!

----
Wat betreft mouse emulation vrees ik dat ik niet helemaal duidelijk was in mijn vorige antwoord.
De mouse emulation zorg ervoor dat alleen muis-specifieke codes doorgestuurd worden.  De mouse emulation moet ook actief zijn als u wil switchen met de muis: met het klikken van het scrollwieltje (moet geactiveerd worden via Hotkey Setting Mode).
Hetzelfde geldt voor de keyboard poort: deze kan alleen standaard keyboardcodes doorsturen.  Daardoor worden ook de specifieke codes gecapteerd om het schakelen met Hotkey te doen.   Bij het uitschakelen van de emulatie vervalt die mogelijkheid.
Gaming toetsenborden en multifunctionele muizen (met extra knoppen) doen net wat meer, wat door de emulatie geblokkeerd wordt.  Door de emulatie uit te zetten, kan dat net voldoende zijn om net die extra functionaliteit toe te laten.  Hetzelfde geldt voor Keyboard/muis combo’s met een unified receiver.  Die worden normaal gezien ondersteund op de Keyboard/muis poort.  Voor exotischer gevallen is echt een speciale driver nodig, en dan voldoet de keyboard of muispoort niet meer, maar is een poort met volledige USB-ondersteuning nodig.
 
Wat betreft de monitorverbinding van de PC via de switch:
De switch leest bij het opstarten de EDID uit van de monitor en slaat dat op.  De PC’s worden bij het switchen dus niet “losgekoppeld” maar blijven het scherm “zien” met die EDID.  Het uitlezen van de EDID kan via Hotkey Setting Mode geforceerd worden, bijvoorbeeld als je even een andere monitor aansluit op de switch.
 
Wat betreft DDC:
DDC is het datakanaal waarover de EDID uitgelezen wordt.  Dat daar verschillende manieren voor bestaan is minder belangrijk, zo lang de EDID informatie maar uitgelezen kan worden.   
DDC komt in diverse implementaties, waarbij DDC2B de meest gebruikte is, voldoende voor het uitlezen van de EDID.
Gebruikt u een speciale toepassing waarbij de meer uitgebreide mogelijkheden van andere DDC-versies nodig zijn?
 
Kind regards / Met vriendelijke groeten / Cordialement / Mit freundlichen Grüßen,

Jurian Blok
Customer Service Center

Karma...

devnullius

[devnullius]

(translated from original Dutch correspondence: http://scforum.info/index.php/topic,8018.msg20288.html#msg20288)

----- Feb. 23, '13.
DEVNULLIUS

Q: When USB mouse emulation is OFF, how is contact maintained with the CPU? When you remark that regular mouses will work, I'm surprised that a wireless keyboard (with dongle) wouldn't work... Because that hints that some other mice & keyboards secretly will give problems too...?
And when mouse emulation is off, can I still use hotkey combo? And same question, but with mouse connected to the USB hub?

Q: EDID... Can you tell me more about technology used? I see all kinds of terminology passing me by, but is DDC better than DDC2 better than DDC2B(i)? Do you support full DDC support?

Q: EDID... As far as I understand it, the CPUs do not have a constant-on connection with the KVM Switch? So, in fact only 1 CPU at any give time can be connected with a screen (or thinks it has the connection!).

Thank you for your patience, truly appreciated!



-----
Jurian Blok @ ATEN Support

I apologize that my last answer concerning mouse emulation doesn't appear to be clear enough.
Mouse emulation makes sure that only mice specific control codes are passed on. Mouse emulation also has to be active when you want to switch on mouse control: click the mouse wheel (this option should be enabled in Hotkey Settings Mode).
The same thing holds true for the keyboard port: this can only transfer default keyboard codes. This also makes sure that specific codes are accepted to use hotkey switching. When emulation is disabled, you will lose this ability.
Gaming keyboards & multi-purpose mouse (with extra buttons) do more. Emulation will block these extra control commands.  When emulation is disabled, this could be (just) enough to enable extra control commands from complex keyboards & mice. This even holds true for keyboard/mouse combo's with a unified receiver. In general, they are supported at the keyboard/mouse port of the KVM Switch. For more exotic models there really is a specialized driver needed. Keyboard or mouseport of the KVM will not suffice anymore. A port with complete USB support is needed.

Concerning the monitor connection of the CPU PC through the switch...
When the switch starts, it reads the EDID of the screen and stores it. So the CPUs will not be disconnected but will always "see" the EDID. If you, for example, attach another screen to the KVM Switch, one can force a re-read of the EDID information (through hotkey settings mode).

Concerning DDC:
DDC is the data channel over which the EDID information is read. There are different ways to do this, but that is less important AS LONG as EDID information can be read.
DDC comes in different flavours, where DDC2B is the most common and widely used one. This will suffice reading any EDID.
Do you use a special application where the more advanced features of (full) DDC-mode versions are necessary?

Kind regards,

Jurain Block ATEN


----
Karma...

devnullius


 

[wiper]

Hi

I'm sorry to ressurect this old thread, but I've found myself in a similar hell, so I'm wondering if there was any conclusion to this.

Currently I'm using StarTech 4 port displayport switch. While it works there are few issues:

• When source computer has not loaded system (it's in bios or boot menu) the keyboard keys often get 'stuck'. Pressing another key will 'fix' it, but still annoying. Maybe it does not like my wireless keyboard.
  
• Sometimes after switching display goes to sleep and I have to poweroff/on the display. This happens after loading windows startup screen (always), and when switching sources with newest versions of nvidia drivers (331 works fine, anything later and the monitor goes to sleep when I switch back). Nvidia support told me that they don't support KVM switches and similar things and suggested to the older drivers that are working. So thre is a concern if I'm stuck with the old drivers forever.

There is also some feeling on keyboard lag sometimes, but that might be in my head (or because the wireless keyboard receiver is now located behind the KVM switch - it might interfere with singal).

Because of the described issues I'm podering if a higher quality switch (this was the cheapest one with displayport support) would work better. Also I'm looking into buying a new monitor with nvidia g-sync support, which requires displayport 1.2 - so this really narrows down the list (of course there are no guarantees that g-sync would work with kvm switches at all).

I could find only two switches with displayport 1.2 support - both are secure switches (belking and the HighSecLabs you've mentioned earlier). I understand they offered you to buy  HighSecLabs K504 switch and then send back if it does not work as expected - did you took up on this offer?