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GTX 285 vs 2 X 4870 in crossfire

Alright, well I went ahead and ordered 2 XFX cards. I'll flash 1 with the new ROM, see if it works, try using with a second card in crossfire without flashing that one, if they work then I'll keep them.

Now for the power, I'm hoping that single SATA will provide enough power for each card (I'm splitting the power half and half). The next thing is figuring out how to get the cables down from up there, since the door closes flush and doesn't leave any space. There is however a small 1cm hole at the front of the machine. I think I'll have to yank off the end of the molex connectors and splice the cables together after passing them through the hole.

If that doesn't work, what about getting a PCI card for internal SATA ports and using an adapter on that to power the graphics cards??? Anyone ever try that before?
 
Well the cards arrived. Right now I have the apple 4870 in with the XFX card linked with crossfire. I booted up in windows (no flashing) and it ran just fine, no crossfire though and no change in benchmarks. Ran in OSX and everything is normal. System profiler shows the second 4870 with the same ROM and EFI (even though it is still the PC ROM). The XFX is also behaving well with the fan humming along quietly, not running at full speed. That was the goal of my test so far, to see if A) the cards computer would boot with 2 cards B) there would be sufficient power to both cards C) that an unflashed 4870 linked with crossfire would behave well under OSX (so I only need to flash 1 of the 2 cards).

I have each card powered half and half with the mother board and the ODD SATA connector. Seems fine to me.

I am now going to remove the apple card and flash one of the XFX cards. Wish me luck.
 
Ok, well I finally managed to flash the XFX card and it worked fine in both windows and OSX. One thing though is a very annoying buzzing when it is working hard. The higher the FPS the higher pitch the buzz. It is quite loud and was not at all present with the apple 4870. I swapped one XFX for the other non-flashed one and it also exhibits the same behavior, so it isn't a defective card.

Can anyone with a PC 4870 comment on that? I seem to remember my X800 doing that in my old G5, but I didn't think modern cards still do that.
 
Did you get a chance to test the two PC cards installed at the same time under OS X and crossfire'd in Windows?
 
Yes and everything works fine, no power issues. I flashed 1 of the 2 cards and running OSX everything is just fine (of course no crossfire available). In windows crossfire works and makes a big difference in some games. However it is clear to me why apple does not support crossfire in OSX yet. It simply isn't ready. There are lots of minor graphical glitches from flickering clouds to faint dark rectangles stretching across the screen. Some games work great with it though with no glitches. However, you can disable crossfire on the fly, so if it causes problems you just disable it.

Biggest problem for me though is the very loud buzzing I am getting. I think the cards may be somewhat defective or just a bad batch. It is nothing that would damage the cards or computer, but it is very very annoying. I might RMA these cards and try another pair, maybe try a different brand, but if that doesn't work I'm just going to get a 285. Like I said, when it works it works great, but the buzz I am experiencing is too much.

And the buzz is present no matter what. I have tried connecting the display to different ports, using 1 card with just the apple 6-pin connectors, trying both cards separately, underclocking them, overclocking them, flashed or unflashed.

It's worth noting though that I haven't seen anyone else on this forum who flashed an XFX card report the buzzing sound.
 
just thought I would drop my notes here, originally when I had the Apple ATI oem 4870's crossfire was a no go. Just recently I put Win7 x64 with the latest drivers from ATI (9.11 package) and it has allowed me to enable crossfire. So no issue with the Apple OEM 4870 cards from what I can report. I haven't been able to find anyone else who can test it but in my case I can confirm it is 100% working in crossfire.
 
matthew.russo said:
just thought I would drop my notes here, originally when I had the Apple ATI oem 4870's crossfire was a no go. Just recently I put Win7 x64 with the latest drivers from ATI (9.11 package) and it has allowed me to enable crossfire. So no issue with the Apple OEM 4870 cards from what I can report. I haven't been able to find anyone else who can test it but in my case I can confirm it is 100% working in crossfire.
Click to expand...

That's a very interesting find!!! Everyone here had assumed Apple or ATI had intentionally borked CF in firmware... now we know it was just a driver or OS issue. Good stuff! :)
 
matthew.russo said:
just thought I would drop my notes here, originally when I had the Apple ATI oem 4870's crossfire was a no go. Just recently I put Win7 x64 with the latest drivers from ATI (9.11 package) and it has allowed me to enable crossfire. So no issue with the Apple OEM 4870 cards from what I can report. I haven't been able to find anyone else who can test it but in my case I can confirm it is 100% working in crossfire.
Click to expand...

That's very interesting to hear since I have a second Apple 4870 and wanted to install it in my Mac Pro for gaming purposes in windows however, the fact that crossfire was disabled made me cancel this idea. However, this has sparked new hope. Just one question, by installing a second Apple 4870 and an addition ODD power supply would I be voiding the Applecare warranty?
 
ildondeigiocchi said:
That's very interesting to hear since I have a second Apple 4870 and wanted to install it in my Mac Pro for gaming purposes in windows however, the fact that crossfire was disabled made me cancel this idea. However, this has sparked new hope. Just one question, by installing a second Apple 4870 and an addition ODD power supply would I be voiding the Applecare warranty?
Click to expand...

Its been mentioned many a time that running the second card off the sata and/or pata connections are ok. But to the point, i think modifying it in any away apart from what is intended would void your warranty. But what is to stop you removing what you added when you have to bring it in to get repaired if need be....
 
matthew.russo said:
Its been mentioned many a time that running the second card off the sata and/or pata connections are ok. But to the point, i think modifying it in any away apart from what is intended would void your warranty. But what is to stop you removing what you added when you have to bring it in to get repaired if need be....
Click to expand...

That's true... however, before i continue with this idea i want to see that other users have been able to enable crossfire under windows 7 which I will be upgrading to.
 
Both 4870's you have running in Crossfire are Apple OEM versions or is one of them a PC (XFX) version because both of mine are Apple 4870's.
 
Nice setup... I have a question though... I saw that you used a ODD power supply. Does it constantly stay on or only once the computer starts?
 
ildondeigiocchi said:
Nice setup... I have a question though... I saw that you used a ODD power supply. Does it constantly stay on or only once the computer starts?
Click to expand...

I had a hell of a hard time finding one to suite. The answer is that it turns on when the PC turns on. It is initialised by a PATA power connector. Simple, smart and it works.

If you looking at fitting it into an 06 or 09 mac pro check first if it can fit, mainly the cables. I had a hard enough time on the 08 mac pro but got it. The 08 model has a hole where the CD tray is to get the cables through. Any questions though regarding my install let me know.
 
chiefroastbeef said:
Do you have any cooling issues with two cards running max on games?
Click to expand...

Nope, it runs cooler than my 8800GT and quiter. The desk it is in is rather closed in so no the best airflow in there either. I found when CF wasn't working it ran hotter than when CF is working. The cards work less.
 
That is awesome! Yea I look at your last picture and saw how claustrophobic your mac pro is (computer rights violation), it must be a pain taking that out and servicing it! That is a very clean setup as well! Where did you get that stand holding up your right screen?
 
chiefroastbeef said:
That is awesome! Yea I look at your last picture and saw how claustrophobic your mac pro is (computer rights violation), it must be a pain taking that out and servicing it! That is a very clean setup as well! Where did you get that stand holding up your right screen?
Click to expand...

haha yeh, the desk is a bit more cleaned up (got a wireless printer) got rid of other clutter under the desk really, been meaning to cut a bit of a bigger hole behind the mac pro but it vents enough hot air over the top of it. Not the worse thing to take out and work on.

It is a Kensington Smart Fit Monitor Stand http://www.kensington.com/
 
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