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Confirmed: Dual-link adapters required for 3 DVI monitor setup on 5870

S

sboerup

macrumors 6502
Original poster
Mar 8, 2009
421
14
I was excited about possibly using all 3 of my monitors on one GPU. What I wasn't excited about was buying the expensive dual-link adapters to run 2 of them. According to Apple, if you have 3 DVI monitors, you need 2 dual-link DVI > MDP adapters to run them all. SO GAY.

I have a 30" Dell and (2) 20" Dell monitors. Since I received my 5870, I've only been able to run 2 monitors: the 30" with the DVI cable, and a 20" with a cheap Monoprice DVI > MDP cable. Worked fine.

So, I found (2) Apple Dual-link adapters on eBay for $39 each and decided to pick them up, as my 2600XT GPU wasn't working with the new 2010 mac with the 5870 attached as well.

As Apple stated, you need (2) dual-link adapters. I tried plugging just one of the 20" monitors and keeping the Monoprice cable in the other but it didn't work. Not surprised. But the bigger surprise was this: You MUST use the USB cable on the adapter, like, it MUST be plugged into your mac for it to work. This takes up 66% of the USB ports on the back of your Mac JUST to run the displays.

To say the least I am extremely disappointed in this crap. Now off to find a USB PCI card to add the needed USB ports.
 
To add to the pain, you CAN plug in other USB devices that used to be plugged into the machine into the adapter . . . but they don't provide the same amount of power. So, plugging in my iPhone will no longer charge it.
 
Had the same issue. I bought a GT120 instead of buying a hundred dollar cable.
 
I'm confused. The dell 30-inch is dual-link, but the 20-inch models, aren't they single-link?

If so, why couldn't you just use the dual-link DVI port for the 30-inch and then use 2 MDP-DVI ($19) for the single-link DVI monitors?

Or are you saying that is not a valid configuration? According to Apple? and/or you just couldn't get that setup to work?

On other note, the dual-link adapters are such crap. $99 and they barely work. I've fought with mine, Macbook Pro 17-inch to Apple 30-inch since day one. The absolute must terrible experience I've had with an Apple product to date. Fuzzy screens, blank screens waking from sleep, etc, etc.
 
The USB port is necessary since the MDP-to-dual-link adapter actually requires power, its not a simple adapter of just re-routing wires, it actually has to do some signal processing... Probably the reason for the $99 price tag also..

Again, not saying its right or anything, but the reason for the needed USB. You can instead of a PCI usb card, just get a self-powered USB hub and plug that into the adapter's USB port, solving the power issue.
 
I believe that the dual-link DVI adapters do have a USB port on them, so at least you haven't lost 66% of your USB ports. I agree that these adapters are very finicky and have caused me great angst at times.

I've got a dual dell u2711 set-up and will be getting two DP->MDP cables to hook them up to my 5870 card.
 
wally21 said:
I believe that the dual-link DVI adapters do have a USB port on them, so at least you haven't lost 66% of your USB ports. I agree that these adapters are very finicky and have caused me great angst at times.

I've got a dual dell u2711 set-up and will be getting two DP->MDP cables to hook them up to my 5870 card.
Click to expand...

The problem with the USB on the adapter is that its under-powered. So without plugging into a powered hub (or a usb hub on your display), the port essentially goes from powered to unpowered.
 
jedijoe said:
The problem with the USB on the adapter is that its under-powered. So without plugging into a powered hub (or a usb hub on your display), the port essentially goes from powered to unpowered.
Click to expand...


That's probably true. I've never actually tried plugging anything into it.
 
sboerup said:
I was excited about possibly using all 3 of my monitors on one GPU. What I wasn't excited about was buying the expensive dual-link adapters to run 2 of them. According to Apple, if you have 3 DVI monitors, you need 2 dual-link DVI > MDP adapters to run them all. SO GAY.

I have a 30" Dell and (2) 20" Dell monitors. Since I received my 5870, I've only been able to run 2 monitors: the 30" with the DVI cable, and a 20" with a cheap Monoprice DVI > MDP cable. Worked fine.

So, I found (2) Apple Dual-link adapters on eBay for $39 each and decided to pick them up, as my 2600XT GPU wasn't working with the new 2010 mac with the 5870 attached as well.

As Apple stated, you need (2) dual-link adapters. I tried plugging just one of the 20" monitors and keeping the Monoprice cable in the other but it didn't work. Not surprised. But the bigger surprise was this: You MUST use the USB cable on the adapter, like, it MUST be plugged into your mac for it to work. This takes up 66% of the USB ports on the back of your Mac JUST to run the displays.

To say the least I am extremely disappointed in this crap. Now off to find a USB PCI card to add the needed USB ports.
Click to expand...

Wow you're right, Apple has a support doc on it:

http://support.apple.com/kb/HT4279

Among other things, it says:
To connect three DVI displays at once, you must use two Apple Mini DisplayPort to Dual-Link DVI Adapters (sold separately).
Click to expand...
Note that it doesn't make a distinction between single link and dual link DVI displays.
 
DualShock said:
Wow you're right, Apple has a support doc on it:

http://support.apple.com/kb/HT4279

Among other things, it says:

Note that it doesn't make a distinction between single link and dual link DVI displays.
Click to expand...

Man that's crap. Here goes Apple trying to shove another display connector down our throats.. Though mini-display port is at least a VESA standard now.. but there are a lot of displays still using DVI and regular displayport.. not to mention Apple only has one monitor choice come September...
 
Yes, I discovered all of this about 2 weeks ago when I bought my Mac Pro. I was planning on keeping my 2600XT to just run the other 2 displays via DVI off them. It didn't work in my machine so I went with adapters rather than the GT120 . . . now I'm kinda wishing I went that route though. Guess I could always sell these adapters.
 
I'm pretty sure you can attached one of the USB cables from one adapter into the USB of the other adapter. Also if you want, you can get an USB extension cable and plug the USB into a wall charger (like the iPod USB charger brick); that's what I did.
 
I'm confused (happens a lot)...

Am I not able to attach one 30" monitor to my 5870 dual-link DVI port and, say, a 24" monitor to the 5870 MiniDisplay port via MDP to DVI adapter?
 
Might be time to start using Display Port...newer monitors are shipping with it.

In all honesty, I wouldn't even consider this card if I wasn't planning to run at least one (preferably two) displays with DP.
 
reel2reel said:
Am I not able to attach one 30" monitor to my 5870 dual-link DVI port and, say, a 24" monitor to the 5870 MiniDisplay port via MDP to DVI adapter?
Click to expand...
AFAIK, you can. This issue only relates to running any 3 DVI monitors.

Can someone test 3xVGA?
 
Weepul said:
AFAIK, you can. This issue only relates to running any 3 DVI monitors.

Can someone test 3xVGA?
Click to expand...

Yep, I think you're correct. I was just reading the support page: http://support.apple.com/kb/HT4279

It seems to affect only three monitors running off the one card. Probably just better off getting a second card unless you can't spare the PCI slot? The adapters are 100+ bucks, aren't they?
 
Yes, I was using a 30" and a 20" just fine, no problems. The 2 MDP displays also don't wake up very gracefully . . . I have to power them off and then on again for them to display properly.
 
sboerup said:
I have to power them off and then on again for them to display properly.
Click to expand...

Gah, that sucks. Is that because of the adapters or the monitors or is it just a MDP fact of life? You'd think this stuff would be tested somewhat before companies start throwing it onto video cards for the masses.
 
reel2reel said:
Gah, that sucks. Is that because of the adapters or the monitors or is it just a MDP fact of life? You'd think this stuff would be tested somewhat before companies start throwing it onto video cards for the masses.
Click to expand...

I've never had to do this before when it was straight DVI, or even with 2 monitors and non-apple adapters. It really is quite lame.
 
I haven't seen it confirmed anywhere else, so I just thought I'd mention it here: I picked up a pair of active Mini-Displayport to DVI single link (Accell B087B-006B) and can confirm that they work on a 2010 Mac Pro with a 5870 card. I can drive three DVI monitors at 1920x1200 by using two of these and the DVI port for the third one.
 
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