[Parts Check] Does anyone know why my KVM does this?

Author	All Replies
Johnny Premium join:2001-06-27 Atlanta, GA kudos:2	[Parts Check] Does anyone know why my KVM does this? Hey, Below is a message I sent to IOGEAR to see if I should buy a KVM that supports a bigger resolution. Basically, my Dell Optiplex 780 SFF with a DVI card works fine through the IOGEAR 2-port switch noted below, but the Mac Pro (Radeon x1900XT) does not. Without the switch, the Mac Pro works fine with the display. Just wondering if anyone had this KVM switch or knew why it won't drive the display from the Mac (but will from the PC). Thanks Message I sent to IOGEAR tech support: I currently have an IOGEAR GCS932UB KVM switch, which works fine to share my 20-inch Apple DVI display between a Dell PC and an original Mac Pro. I recently bought an Apple 27-inch LED Cinema Display and connected it up to the IOGEAR. The IOGEAR displays the PC video fine, but will not display any video from the Mac Pro (Radeon X1900 XT card). IMPORTANT: I am using a ATLONA DVI-to-mini-Displayport converter to connect the IOGEAR to the LED Cinema Display. As above, this works with the PC but not the Mac. There is nothing wrong with the monitor, or the Mac, as if I REMOVE the KVM switch from the setup, and plug the Mac directly into the Apple LED Cinema display through the ATLONA converter, it works perfectly. So my question is, is the IOGEAR GCS932UB KVM switch which I am using not sufficient to drive the Apple 27-inch LED Cinema Display? If that seems to be the issue, then I will buy a new IOGEAR switch. Will the IOGEAR GCS982U switch (with its higher resolution support) drive the Apple display through the DVI-to-miniDisplayport adapter?
	to forum · permalink · 2012-03-24 21:00:54 ·

signmeuptoo Thank you Yankees Premium join:2001-11-22 NanoParticle kudos:4	Sure wish I could help you. I think the OS is the issue though.
	to forum · permalink · 2012-03-24 21:57:49 ·
sk1939 Premium join:2010-10-23 Washington, DC kudos:9	reply to Johnny The question is, what resolution are you driving the displays at? My Avocent doesn't have an issue with either my Optiplex or the Mac Pro.
	to forum · permalink · 2012-03-24 22:14:30 ·
antbhill2 Premium,MVM join:2001-02-28 Northern VA	reply to Johnny Agree with SK1939. Rated resolution of the KVM switch is 1920 X 1200. It appears your monitor is capable of 2560-by-1440. So you may have to reduce the resolution to use that switch.
	to forum · permalink · 2012-03-24 22:22:07 ·
Camelot One Premium,MVM join:2001-11-21 Greenwood, IN kudos:1	said by antbhill2: Agree with SK1939. Rated resolution of the KVM switch is 1920 X 1200. It appears your monitor is capable of 2560-by-1440. So you may have to reduce the resolution to use that switch. I have the same problem with my Dell 30". None of the cheap KVMs I have on hand can pass it's native 2560x1600. For that matter, most of the DVI to Display Port adapters I have seen are single link, not dual. (and I think at 1560x1440, you would need dual link DVI.)
	to forum · permalink · 2012-03-24 22:54:01 ·
drew Automatic Premium join:2002-07-10 Port Orchard, WA kudos:6	reply to Johnny The above are correct - the KVM can't drive that resolution. IOGEAR has a KVM (»www.iogear.com/product/GCS1212TAA/) that'll do it... spendy. Searching for dual-link kvm shows a high price tag. -- flickr \| Of faith, power and glory
	to forum · permalink · 2012-03-24 23:22:29 ·
sk1939 Premium join:2010-10-23 Washington, DC kudos:9 Reviews: ·T-Mobile US 1 edit	reply to Camelot One said by Camelot One: For that matter, most of the DVI to Display Port adapters I have seen are single link, not dual. (and I think at 1560x1440, you would need dual link DVI.) Well sort of. Single-Link DVI will handle resolutions up to 2,098 -1,311 @ 60 Hz, but only IF the clock frequency is 165Mhz or lower and has at most 24 bits per pixel. Otherwise modes that require more than 24 bits per pixel, and/or 165 MHz pixel clock frequency use the Dual-Link mode. For example, Single-Link will support a display resolution of 3,840 - 2,400, but only at a slideshow refresh rate of 17Hz. Dual-Link by comparison will support the same resolution at a more playable 33Hz. Your monitors resolution of 2,560 - 1,600 uses two 135 MHz channels, so Dual-Link is required for the maximum resolution. Also note that your adapter ( ATLONA DVI-to-mini-Displayport converter) only supports resolutions up to 1920x1200. Likewise, your KVM only supports resolutions up to 1920 X 1200 @ 60 Hz with 32 bit color. As far as a new KVM goes, I suggest this one: »www.newegg.com/Product/Product.a···17791101 Edit: IOGear makes two alternative options for a considerably cheaper price. »www.amazon.com/IOGEAR-2-Port-Dua···4&sr=1-6 »www.amazon.com/IOGEAR-2-Port-Dua···4&sr=1-3 You will also need an updated version of your adapter (you have the AT-DP200): »www.amazon.com/ATLONA-AT-DP400-D···2&sr=1-1
	to forum · permalink · 2012-03-24 23:31:37 ·
Johnny Premium join:2001-06-27 Atlanta, GA kudos:2	reply to sk1939 said by sk1939: The question is, what resolution are you driving the displays at? My Avocent doesn't have an issue with either my Optiplex or the Mac Pro. That's gotta be the key. I think XP doesn't try to offer anything more than the IOGEAR can handle, whereas the Mac will use the full display capability, which is too much for the switch. I am using the Atlona DP-400, and as I said, with the KVM switch out of the loop, that works fine, full resolution, even my ancient MacBook Pro (2007) can drive the 27" and mirror, no problem. This confirms my suspicion that I need to buy a new switch. PC works, Mac works, display works, and the Atlona works, so a new switch is in order. Thanks to all. As soon as I get the new switch I'll check back.
	to forum · permalink · 2012-03-25 01:15:02 ·
Johnny Premium join:2001-06-27 Atlanta, GA kudos:2	reply to sk1939 said by sk1939: Your monitors resolution of 2,560 - 1,600 uses two 135 MHz channels, so Dual-Link is required for the maximum resolution. Also note that your adapter ( ATLONA DVI-to-mini-Displayport converter) only supports resolutions up to 1920x1200. Likewise, your KVM only supports resolutions up to 1920 X 1200 @ 60 Hz with 32 bit color. »www.amazon.com/IOGEAR-2-Port-Dua···4&sr=1-6 Thanks for the reply. Going to order the GCS982U switch - I don't need 7.1 audio. Hopefully can try it out in a few days. My Atlona is already the DP-400 one, so I'm set there. I didn't see an IOGEAR switch that came with mini-displayport output. If anybody saw one, please let me know.
	to forum · permalink · 2012-03-25 01:33:03 ·
sk1939 Premium join:2010-10-23 Washington, DC kudos:9 Reviews: ·T-Mobile US	The only one I've seen that even use's DP is this Geffen: »www.newegg.com/Product/Product.a···DP%20KVM , and that's not mini-DP, just regular DP.
	to forum · permalink · 2012-03-25 12:53:09 ·
Johnny Premium join:2001-06-27 Atlanta, GA kudos:2	No biggie. I'm just glad I didn't have to get a new Mac Pro yet, because nobody knows if there is even going to be one. New switch should be here end of week.
	to forum · permalink · 2012-03-25 12:55:50 ·
sk1939 Premium join:2010-10-23 Washington, DC kudos:9 Reviews: ·T-Mobile US	Certainly saves you on making a major purchase. You many also want to consider picking up one of these for future use: »www.newegg.com/Product/Product.a···12200691 That being said, how do you like the new Cinema compared to the older revisions? I'm not a fan of the price tag, but I am curious quality-wise.
	to forum · permalink · 2012-03-25 13:01:40 ·
Johnny Premium join:2001-06-27 Atlanta, GA kudos:2	Very sharp, I like the glossy (don't know why, but I do), built-in camera recognized by the Mac so I don't have to whip out the iPad for video conference, has a MagSafe cable so I can power my MacBook Pro while using it for mirroring in case the desktop goes down, and the usual 3 USB ports. Have to see if those ports have enough oomph to charge the iDevices. Usually I get a refurb, but there weren't any available at the time I picked this up in-store. The refurb is $849 I believe.
	to forum · permalink · 2012-03-25 13:34:19 ·
sk1939 Premium join:2010-10-23 Washington, DC kudos:9	See, I don't care for the glossy screens mostly because I can't stand the glare they give off in direct light. How is the color?
	to forum · permalink · 2012-03-25 13:50:51 ·
Johnny Premium join:2001-06-27 Atlanta, GA kudos:2	Much richer than the old 20" this is replacing. I suppose that is true for any upgrade of a display over the years. There's no yellow cast that some new displays have been said to have.
	to forum · permalink · 2012-03-25 14:53:15 ·
sk1939 Premium join:2010-10-23 Washington, DC kudos:9	Nothing can compare to the old CRTs though as far as refresh and black levels. I hadn't heard that. I personally am looking at the HP Dreamcolor, although it's still rather pricey for my taste.
	to forum · permalink · 2012-03-25 15:19:14 ·
Johnny Premium join:2001-06-27 Atlanta, GA kudos:2	Continuing this saga - I received the IOGEAR GCS982U switch. Swapped it in for the other switch, and now with both PC and Mac connected, the Mac display works. Sort of. I'm thinking there is some setting in the switch that I had made with the other one and I need to make with this one. - the PC doesn't display anything at all. Nada. Strangely, it did with the other switch and the exact same setup. The switch's LED shows 2 PCs connected. - Switching to the PC, and then back to the Mac, now results in a dead screen. I have to press the Reset button on the ATLONA PCI converter to get the display back. I have no idea what's causing this. It was NOT an issue with the 932U switch. So - still not a smooth setup. I can use my monitor with the Mac through the switch now (unlike before), but these new issues arise. 1. Does anyone know what I might need to do on a Windows boot to set something about the display? I know zero about Windows. 2. Does anything come to mind as to what might cause a PC not to want to display through this switch, when it DID display through the other (lower-res) switch? Any KVM settings that I need to flip? 3. Any other tips greatly appreciated.
	to forum · permalink · 2012-03-31 16:22:07 ·
drew Automatic Premium join:2002-07-10 Port Orchard, WA kudos:6	What resolution ( and connection ) is the PC using? I am concerned about resolution that the PC is running is whacked out. -- flickr \| Of faith, power and glory
	to forum · permalink · 2012-04-01 10:31:05 ·
Johnny Premium join:2001-06-27 Atlanta, GA kudos:2	said by drew: What resolution ( and connection ) is the PC using? I am concerned about resolution that the PC is running is whacked out. DVI, to the switch. Well, I can't really tell the resolution since the PC isn't on the display. Can I boot it into a mode that will display no matter what, and set the resolution from there? It always says something about F12 when it boots...
	to forum · permalink · 2012-04-01 10:49:49 ·
Johnny Premium join:2001-06-27 Atlanta, GA kudos:2	reply to drew OK, I put a separate keyboard on the Dell, hold down F12, and I can get it to proceed to the "Windows XP" progress bar that appears right before the desktop should start loading, but nothing beyond that. And, every time I switch back to the Mac after the PC has a blank screen, I have to reset the DVI-to-miniDisplayport converter. What settings should I make, or how do I boot the PC in "default video" mode?
	to forum · permalink · 2012-04-01 11:40:41 ·

Technical > PC Hardware Discussion/Reviews > [Parts Check] Does anyone know why my KVM does this?