I need a Mac/Monitor/keyboard switcher for DisplayPort Monitor

machenryr

macrumors 6502a
Original poster
Jan 25, 2016
563
76
I need some help over here. I have two Mac Pros, 2009/2010 3.46 5,1 machines. But I only have one monitor. Before I got a new monitor a couple of months ago I used an IOGear KVM switcher. Cheap. Worked great. But the new monitor, Samsung, uses DisplayPort/HDMI. I can't use that because it used DVI. So I got two adaptors - mini-DisplayPort to DisplayPort. But I need a new switcher. I need to share the monitor and keyboard/USB. Any ideas? I don't need 4 ports, just two.
 

AidenShaw

macrumors P6
Feb 8, 2003
18,635
4,633
The Peninsula
I need some help over here. I have two Mac Pros, 2009/2010 3.46 5,1 machines. But I only have one monitor. Before I got a new monitor a couple of months ago I used an IOGear KVM switcher. Cheap. Worked great. But the new monitor, Samsung, uses DisplayPort/HDMI. I can't use that because it used DVI. So I got two adaptors - mini-DisplayPort to DisplayPort. But I need a new switcher. I need to share the monitor and keyboard/USB. Any ideas? I don't need 4 ports, just two.
iogear.com has a "mDP" and "DP" category under "KVM products"

https://www.iogear.com/solutions/kvm/?filters=18|138
 

Biped

macrumors regular
Sep 7, 2017
174
202
Stay far far away from Startech when dealing with mac.

I made that mistake previously.
 

frou

macrumors 6502a
Mar 14, 2009
821
902
In my experience, it's more reliable to plug the computers into separate video inputs on the monitor, and use a plain USB switch (as dumb as possible) for the K/M.
 

machenryr

macrumors 6502a
Original poster
Jan 25, 2016
563
76
Got the Star-tech today. I can’t get the 2nd Mac Pro to work. I got the DisplayPort 2 Port version. I tried switching cables. I shared the screen to make sure the Mac was running correctly. And it was. Then I even hooked it up directly to eliminate the switcher issue. And I couldn’t get a direct connection either. But I easily switch to MP#1. But switching to MP#2 brings me just a black screen.

So a couple of things. This MacPro #2 has never seen this Samsung DisplayPort. It’s used the DVI connection with the last iogear switcher. Also it’s running Yosemite and the main Mac is Sierra. Do I need to upgrade to at least Sierra?

Or can it be the graphics/video card?

I’m using a mini display to DP adaptor.
 

machenryr

macrumors 6502a
Original poster
Jan 25, 2016
563
76
Anyone have any tips? Could it be Yosemite and Sierra not mixing? I did this before when they were both Yosemite. Is it just the Startech? How can I check the video card? I guess I can take one out of the one and put it in the other.
 

bookemdano

macrumors 65816
Jul 29, 2011
1,318
744
Got the Star-tech today. I can’t get the 2nd Mac Pro to work. I got the DisplayPort 2 Port version. I tried switching cables. I shared the screen to make sure the Mac was running correctly. And it was. Then I even hooked it up directly to eliminate the switcher issue. And I couldn’t get a direct connection either. But I easily switch to MP#1. But switching to MP#2 brings me just a black screen.

So a couple of things. This MacPro #2 has never seen this Samsung DisplayPort. It’s used the DVI connection with the last iogear switcher. Also it’s running Yosemite and the main Mac is Sierra. Do I need to upgrade to at least Sierra?

Or can it be the graphics/video card?

I’m using a mini display to DP adaptor.
Easiest way to eliminate everything but the 2nd Mac Pro's video card is to directly connect the 2nd Mac Pro to your monitor via DisplayPort (eliminate the KVM) with the Mac turned off. Then boot up. Do you still get a black screen? If so then the KVM is not the problem. You mentioned you couldn't get a picture with direct connection but not sure if you tried that by hotplugging or with the power off.

If you get a black screen even with a direct connection, try clearing the NVRAM (easiest to use a wired keyboard for that if you have one). If you don't know how to do that just google Mac clear NVRAM.

You never mentioned what video cards you are using in the two machines. Are they the stock cards or something aftermarket? What resolution(s) are you running? You could try swapping the video cards on the two Mac Pros. Does the problem then move to Mac Pro #1? Then the problem is the video card. If it stays on Mac Pro #2 then perhaps it's a driver or OS issue.
 

machenryr

macrumors 6502a
Original poster
Jan 25, 2016
563
76
Thank you. I'll try somethings later tonight when I get home. I can't remember whether I rebooted after swapping DisplayPort cables. Mac 1 definitely did work with the switched cable.

Is clearing the NVRAM the same as what I call "zapping the PRAM?" Rebooting holding op/command R and P? I can't remember exactly. Something like that. I'll look them both up.

I have a hard time controlling Mac2 without a monitor.
Graphic Cards:
Mac 1 - NVIDIA GeForce GT 120
Type: GPU

Bus: PCIe

Slot: Slot-1

PCIe Lane Width: x16

VRAM (Total): 512 MB

Mac 2 - TI Radeon HD 5770
Type: GPU

Bus: PCIe

Slot: Slot-1

PCIe Lane Width: x16

VRAM (Total): 1024 MB

I don't remember whether they're after market or not. I think I replaced one of them.
 

bookemdano

macrumors 65816
Jul 29, 2011
1,318
744
Edit: Read the last paragraph first!

Sounds like you're using the stock cards. The GT120 was stock for the 2009 and the 5770 was stock for the 2010.

Yep, PRAM/NVRAM procedure is exactly the same. It's definitely worth a try to clear it on the system you're getting a black screen on since some display parameters are stored there.

You should also try using the mini-displayport->displayport adapter and displayport cable from Mac #1 just to rule out an issue with the ones you're using on Mac #2.

Not sure if you are comfortable opening up the two machines to swap video cards but I would try that too.

One other thing in general with a KVM is that the order you connect the cables to the KVM can be important. The KVM has to communicate with the monitor to find out the monitor's native resolution, which the KVM then must communicate to the attached computers. It may be a good idea to connect all the cables to the KVM, power on the monitor, then power on the KVM, then power on each of the computers.

Actually, now that I'm re-reading your original post, here's another suggestion. You can easily adapt HDMI to DVI in either direction (adapters are dirt cheap and very reliable). So you could adapt your new monitor's HDMI port to DVI and just use your old DVI KVM. In my experience DisplayPort is a really finicky, temperamental standard. It's sort of unavoidable right now for people doing 4K resolution, although even that is changing with HDMI 2.0.

Hope something there helps you.
 

machenryr

macrumors 6502a
Original poster
Jan 25, 2016
563
76
Ok. Thanks. I’m swapping the video cards. I put in and take out PCIe cards all the time. But there’s a trick to removing and installing video cards? There’s an unlock bar or something?
 

machenryr

macrumors 6502a
Original poster
Jan 25, 2016
563
76
Hm. I should probably start more basic than switching cards. Lol.
 

bookemdano

macrumors 65816
Jul 29, 2011
1,318
744
Like I said before, if your new monitor has HDMI and you already have a perfectly-working DVI KVM switch then just buy a simple HDMI->DVI adapter and return the DisplayPort KVM. IMHO DisplayPort is a really crappy standard fraught with all kinds of instability and incompatibility. Since you don't appear to be using 4K I really think the simplest (and cheapest) course of action is just to adapt your monitor's HDMI port to DVI and call it a day.

You can get something like this: https://www.amazon.com/AmazonBasics-Input-Output-Adapter-Cable/dp/B014I8UQJY which has HDMI on one end (for the monitor side) and DVI on the other end to plug into your KVM's output.

If the KVM's output cable is captive (permanently attached) then you can get something like this: https://www.amazon.com/StarTech-com-DVI-D-Video-Cable-Adapter/dp/B009YCASUW which has a female DVI connector to plug your KVM's output cable into and an HDMI male connector to plug into your monitor.

DVI and HDMI actually use the same exact video signals, just in different connectors. So HDMI-DVI adapters are very cheap and very reliable.
 
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machenryr

macrumors 6502a
Original poster
Jan 25, 2016
563
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I think you’re right. But I just swapped out the card and it came on. I have put the other card in Mac#1 yet. I’m considering getting a new card.

I’m moving a studio so I can’t really devote all my time to this issue with a lot of testing. I’ll try the Radeon card in #1 now.
 

bookemdano

macrumors 65816
Jul 29, 2011
1,318
744
OK. Well at least you've got options going forward. If you decide to stick with the DisplayPort KVM and get it fully working, please post back here so other Mac users who may find this thread in the future will know if it works with Macs or not.
 
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machenryr

macrumors 6502a
Original poster
Jan 25, 2016
563
76
Hm. Ok. With cards swapped KVM seems to work fine. I think I’ll put them back and see what happens.
 

bookemdano

macrumors 65816
Jul 29, 2011
1,318
744
If it works after you swap them back then you may not have connected everything in the right order the first time. Again, start with everything turned off. Connect the KVM output to your monitor, then connect both Macs to the KVM's inputs. Then power on in this order:

1. Monitor
2. KVM
3. Macs

That should allow the KVM to read the EDID info from the monitor, which it will then repeat to the Macs once they are powered on.
 

machenryr

macrumors 6502a
Original poster
Jan 25, 2016
563
76
Weird, but not altogether surprising because DisplayPort sucks, lol. Well you know what my advice is so I'll refrain from spouting it again. Good luck whatever you end up doing.
Lol!!! Yeah. Ok! But I remember there’s something else strange about this particular Mac Pro #2. It doesn’t shut down. I have to do a hard shutdown from the front button. But it shut down, I think, with the different graphic card. Maybe the problem is in the card. I’ll have to double check that.

I could also try plugging the power cable from the card into the other plug?

This shutdown issue is the reason I favored the 2009 MP as #1 over the mid 2010. Hm.
 

machenryr

macrumors 6502a
Original poster
Jan 25, 2016
563
76
I tried with the Radeon plugged into the other PSU, or whatever. Still nada.
 

machenryr

macrumors 6502a
Original poster
Jan 25, 2016
563
76
I’m sorry. I thought I updated this. Mac#2 fell asleep. I just held the start/Shutdown button for 2 seconds and it woke up. This doesn’t explain the various times I rebooted and got black screen. Maybe it just had to find it.
 
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