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HD7990 + HD7970 in a Motherboard that only supports Dual Crossfire

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  • Dual
  • Crossfire
  • Motherboards
Last response: in Motherboards
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May 7, 2014 5:51:22 PM

I am trying to use a HD7990 and HD7970 in Trifire, in a Gigabyte 990FXA-D3 motherboard, which supports only dual crossfire. But my assumption was that this configuration would work because it only uses two PCI slots.

When i installed the cards, my system can recognise the 3 GPUS, and I get "3 GPUS" in GPU-Z. I can enable CrossfireX in Catalyst.

But whenever I start a game that uses the 3 cards (example, BF4), my system instantly crashes. I tried Tomb Raider, and it stuttered like crazy, and eventually crashed.

I have reinstalled windows 8, and tried BF4 again, same result.

BF4 works on both cards if they are installed on their own. My PSU is Corsair RM-1000

Is this definitely the motherboard's fault? Should I buy a new motherboard?

More about : hd7990 hd7970 motherboard supports dual crossfire

a c 210 V Motherboard
May 7, 2014 6:01:58 PM

cannot find that MB anywhere at gigabyte?
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May 7, 2014 6:21:14 PM

Another thing is my PCI soundcard, ASUS Xonar DSX, seemed to stop working when i was running tomb raider..
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a c 210 V Motherboard
May 7, 2014 6:30:13 PM

For some reason your MB does not show up in searches at gigabyte.us???

The MB manual says that two identical GPU's are needed to crossfire or SLI.

from the manual:
A. System Requirements
-
Windows 7, Windows Vista or Windows XP operating system
-
A CrossFireX/SLI-supported motherboard with two PCI Express x16 slots and correct driver
-
Two CrossFireX/SLI-ready graphics cards of identical brand and chip and correct driver
-
One CrossFire
(Note )
/SLI bridge connector
-
A power supply with sufficient power is recommended (Refer to the manual of your graphics cards for
the power requirement)

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May 7, 2014 6:36:25 PM

So... you're saying that the motherboard cannot support this setup? Would you recommend a different motherboard?
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a c 210 V Motherboard
May 7, 2014 6:43:45 PM

Most all MB's require SLI or Crossfire to have identical GPU's. Some FM2 boards allow different configurations but not using high end GPU's like a 7990 or 7970. Sorry don't know what else to tell you.

The 7990 should kick ass by it's self.
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a c 370 V Motherboard
May 8, 2014 2:48:06 AM

Invictus, you are correct. You can pair those two cards, with that motherboard, it would appear to be you can do that configuration, even though it only has two PCI-E X16 Slots.

the 7990 and 7970 are technically identical, it's basically a 3-way 7970 setup, which two of the 7970's are slightly underpowered.
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a c 210 V Motherboard
May 8, 2014 11:21:46 AM

Cool. That's good to know. Keep up the status. I really want to know if you can get them running together.

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May 8, 2014 8:06:00 PM

With the Gigabyte motherboard, I had huge crashing issues. Reinstalled windows, and refreshed failsafe defaults in the BIOS, with no luck.

I switched to a ASUS M5A99FX-Pro-R2, and it works perfectly straight away. Running BF4 on Ultra 4K, with all AA off, at around 70-80 fps. Super happy!

There must be some limitation in the Gigabyte that means it can't handle 3 GPU's, even if they sit in 2 PCI slots. I suppose this is as per the specification of the mobo.

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a c 370 V Motherboard
May 9, 2014 1:34:36 AM

it really depends on the motherboard, though your One has the capability to support 3 in your config, it really isn't meant to. As for your new motherboard, great choice and great it works.
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