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Running dual 4870's in a 2009 Mac Pro

THe PSU's on the early 2008 Mac Pro's have plenty of juice!

Also To let everyone know REV.1 (2x dual core) Mac Pro's have a 1000W PSU, REV.2s (2x quad core CPU's) have a 1400W PSU. There is plenty of power to spare. As the 2x4 MacPros were designed to run Raid 4drive systems with dual 16x buses for 2 very high end video cards and 8 sticks of ECC Buffered Server memory which can be quite the power hog & dual 3.2ghz Quad core CPUs.
 
matthew.russo said:
I have a question in regard to dual link on these cards.

If I were to connect 2 monitors to one card using DVI only, can I use the normal DVI port and the second output with minidisplay port to DVI cable to connect both monitors?

Also, can 2 cards be used to run 3 monitors in OSX?
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I want to know this too, cause i will be running dual 1080 displays on my table and also be able to connect to my HD TV.
 
Just wanted to add that I've now got two 4870 1GB flashed XFX cards running in Crossfire on my 2006 2.66GHz Mac Pro. I'm using PCIe power y-cable splitters to split each of the board's PCIe power ports into two. So far, so good (touch wood).
 
Spanky Deluxe said:
Just wanted to add that I've now got two 4870 1GB flashed XFX cards running in Crossfire on my 2006 2.66GHz Mac Pro. I'm using PCIe power y-cable splitters to split each of the board's PCIe power ports into two. So far, so good (touch wood).
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Are you sure the motherboard can supply over 50 amps on the 12V rails through the two PCI-Express 6-pin cables for prolonged periods of time?

This could be a disaster waiting to happen. Just saying... ;)

Nothing worse than having to replace the motherboard in these machines, not to mention expensive.

Would be a lot easier if we knew the actual specifications of the power supply.
 
Pressure said:
Are you sure the motherboard can supply over 50 amps on the 12V rails through the two PCI-Express 6-pin cables for prolonged periods of time?

This could be a disaster waiting to happen. Just saying... ;)

Nothing worse than having to replace the motherboard in these machines, not to mention expensive.

Would be a lot easier if we knew the actual specifications of the power supply.
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People have been running dual graphics card on a chip nVidia solutions in these for Windows while having 1900 XTs in there as well for a while. I'll report back if I have any issues but I was playing Crysis last night for a good while and didn't have any problems.
 
Pressure said:
Are you sure the motherboard can supply over 50 amps on the 12V rails through the two PCI-Express 6-pin cables for prolonged periods of time?

This could be a disaster waiting to happen. Just saying... ;)

Nothing worse than having to replace the motherboard in these machines, not to mention expensive.

Would be a lot easier if we knew the actual specifications of the power supply.
Click to expand...

The maximum power output of the 2009 Mac pro's PSU is 980W, and according to this maximum power consumption of the standard 8-core Nehalem is 309W, and of the standard 8-core Harpertown is 318W. Deduct the power of the GT-120 about 60W, We have about 730 W to spare for graphic cards and add-on stuffs.

So extra power supply is not needed for crossfire. I don't know if the 2 PCI-e cables can handle two 4870s using Y split cable in a long run??

I am about to purchase another 4870 and I just want to know if the the Y split cable works, or I need to get juice from different source (e.g. SATA).
 

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iphong said:
I am about to purchase another 4870 and I just want to know if the the Y split cable works, or I need to get juice from different source (e.g. SATA).
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Y split cables work with my 4870s in my 2006 Mac Pro. People did report some stability problems with sucking power from the SATA cables to power graphics cards before although I ran one of my old 3870s from the SATA cables and didn't have any problems. That was back when I hadn't bought the right cables of course.

You're right that these power supplys can easily handle the wattage, the question is if the PCIe connectors can deal with all that power going through them. Its so far so good on my end and like I said, people have split them before to power things like GX2s for Boot Camp before and didn't have any problems.
 
Hey, Thanks. Placing an order for another 4870 now. Just one question of curiosity, how is the 4870 compare to a singled 4870x2? can you point me to some places where there are benchmarks of these 2 setups?

And by any chance you know which game is optimized for ATI crossfire? I know Crysis doesn't run faster with crossfire because it's optimized for SLI.
 
iphong said:
Hey, Thanks. Placing an order for another 4870 now. Just one question of curiosity, how is the 4870 compare to a singled 4870x2? can you point me to some places where there are benchmarks of these 2 setups?

And by any chance you know which game is optimized for ATI crossfire? I know Crysis doesn't run faster with crossfire because it's optimized for SLI.
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There are loads of benchmarks out there. Here's one for example. Basically 4870 x2's are about the same as two 4870s in crossfire. It does vary a little depending on the game because most 4870s in benchmarks are 512MB models whereas each 4870 chip in an X2 has 1GB of memory but then again, the clock speed and memory speed of the 4870 x2 is slightly less than that of a standard 4870.

Crossfire makes a big difference for pretty much every game, it only appears to be Crysis which appears to be specifically handicapped for ATI cards where it doesn't give that big a boost. Having said that, I was playing it yesterday at Very High settings, 2x anti-aliasing at 2560x1600. It wasn't smooth as silk but it was definitely playable.
 
Spanky Deluxe said:
You're right that these power supplys can easily handle the wattage, the question is if the PCIe connectors can deal with all that power going through them. Its so far so good on my end and like I said, people have split them before to power things like GX2s for Boot Camp before and didn't have any problems.
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I'm not sure how the PCIe power connectors get their power delivered on a 2006 machine, but on a 2009 machine, it looks like the power is delivered to the PCIe headers on the logic board via traces on the board... That would be the weakest link for sure!

From past experience, the 6-pin connectors and cables can easily handle the power... splitting them won't cause any issues. What I'd be concerned about is burning out the traces on the logic board that deliver the power from the PSU to the PCIe power headers.
 
Well, how likely is this on a Penryn or Nehalem Mac Pro? It doesn't seem likely, but I don't know anything about power routing on a logic board...
 
Spanky Deluxe said:
Just wanted to add that I've now got two 4870 1GB flashed XFX cards running in Crossfire on my 2006 2.66GHz Mac Pro. I'm using PCIe power y-cable splitters to split each of the board's PCIe power ports into two. So far, so good (touch wood).
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Is that not kind of a waste since the second card will only be running 4x speed instead of 16x?

Anyway, what model NO is the card you are using?
 
Cindori said:
Is that not kind of a waste since the second card will only be running 4x speed instead of 16x?

Anyway, what model NO is the card you are using?
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Nope, both cards are running at 8x speed and since in real life performance 8x doesn't decrease performance that much (~10%) compared to 16x, it doesn't really matter. Besides which, that speed penalty only even kicks in if you saturate the available VRAM on the cards. If you're talking games, there's not very much out there that can saturate 1024MB of VRAM.

I'm using the standard XFX 4870 1GB cards (not the slightly overclocked XXX versions) that many people have had success flashing. Took next to no time using Swissman's guide.
 
Posted this in the 4870 flashing thread but thought it might be worth putting in here too:

Spanky Deluxe said:
Do you remember how much slower?

BTW, Warning for anyone using the 4870, official or flashed: Be careful about the quality of DVI cables you use. I bought a dual link cable off eBay for about £10, didn't seem that cheaply built and digital's digital and all that. However, after using the cable for about ten minutes I started getting speckling and noise on my screen. I got worried that it might be the flashed cards but its not. Plugging my ACD in without the extension cable works just fine with no noise. Try the other cable again, noise after a few minutes. The connector gets pretty hot and so I'm led to believe that the heat these 4870s pump out via the fan slot is sufficient to cause poor quality DVI cables to error.

Of course, I only found this out after I spent all afternoon sorting my office out and moving my Mac Pro to the other side of my desk. Its only a 1m extension cable but its now zip tied to several other cables and hidden away with zip ties under my desk. :(

Now I have to wonder, where on Earth can I get a good quality 1m long dual link DVI extension lead in the UK tomorrow without having to resort to waiting until Monday to have one delivered. :( PC World, Currys and Maplin's all seem to do male to male leads rather than male to female. :( Sitting with my Mac Pro now on its side taking up half of my desk is not the result I was hoping for after all this moving and tidying and zip-tieing!! :p
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frag-master said:
first question are these the mac ones ??? and can you boot into osx and windows.... crossfire only windows ...
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They are both mac cards. I can boot into os x and windows no problem. Crossfire is only supported under windows but even so I am having an issue to get crossfire enabled...not sure if the issue is related to the apple 4870's only. Has anyone come across the issue on any other apple ati cards?
 
matthew.russo said:
They are both mac cards. I can boot into os x and windows no problem. Crossfire is only supported under windows but even so I am having an issue to get crossfire enabled...not sure if the issue is related to the apple 4870's only. Has anyone come across the issue on any other apple ati cards?
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Did you connect the crossfire cable (included or bought)? The cards need to be connected together for crossfire to work.
 
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