Crossfire problems : Please help

[HEADRAT]

Hi,

I've flashed both cards (HIS HD 7950 ICE Q BOOST) with the BIOS to remove the "boost" but if I enable Crossfire any game hard locks within about 1 minute of starting (850W Corsair PSU so plenty of power)

Crossfire is definitely working as the status icon is displayed, also framerate is greatly improved until the lockup!

I've tried both 13.12 and 14.4 but they both do exactly the same!

If I disable Crossfire the games play fine, no lockup, no crossfire status icon, reduced framerates.

Specs are-

Intel Core i7-2600K 3.40GHz
2x HIS ICQ-7950
Corsair HX 850W
Gigabyte P67A-UD3-B3 Intel P67 Chipset
G.Skill RipJawsX 16GB (4x4GB) DDR3 PC3-12800C9 1600MHz
Corsair H70

currently everything running stock.

Anybody suggest anything, were I might be going wrong etc?

HEADRAT

 

[HEADRAT]

Do you still have the stock bios on the other switch, and if so, have you tried it?

Yes, the work fine individually but not in Crossfire.

By any chance is the corsair psu 850hx version?

Yes, it's a Corsair 850HX, I'm hoping that isn't the issue I'm running 1 card off the 2 PCI-E blue connectors on the PSU, the other card off the spider cables that come directly off the PSU.

Hardlock is in every game I've tried as well as things like Heaven Benchmark, I thinks it's a systemic issue rather than being isolated to one game.

Yep MSN afterburner shows usage on both cards and temps OK.

Running everything at stock until I can get Crossfire sorted, normally running at 4.5Ghz

Many thanks for the input, I've tried lots of things and coming to the end of what I can think of now, I'd never considered it being an issue with the PSU as I thought the Corsair HX850 was a good/quality bit of kit well able to run 2 x 7950s in Crossfire. Loathed to buy another PSU just to prove that theory right/wrong!

 

[HEADRAT]

I've only just got the second 7950, maybe I should try running the two cards off the blue connectors on the PSU, I'll try and find a piccy.

 

[HEADRAT]

I've got a feeling I didn't use the other modular cables as they wouldn't reach.

 

[HEADRAT]

Tried modular cables, still crashes.

 

[HEADRAT]

They work fine on their own

 

[HEADRAT]

To get back to stock bios I have to switch the jumper on the card to position 2, right?

 

[HEADRAT]

If I set the jumper on the card to position 2 my machine won't boot!

I had some success last night with "underclocking" my cards, if I set to 800 Core and 1000 Mhz Mem I don't get a crash!

 

[HEADRAT]

Thanks for all the suggestion guys, not going to have a chance until the weekend to tinker.

 

[HEADRAT]

I've tried absolutely everything:-

1. Flashed back to original BIOS
2. Complete re-install of OS then tried both 13.12 and 14.4 drivers
3. Swapped position of cards
4. Tested cards not in Crossfire, both work fine

then only thing I can think it can be is:-

1. P67A-UD3-B3 just doesn't like 7950s in Crossfire (worked fine win 2 x 6950s)
2. Corsair HX 850W just isn't cutting it.

thanks for all the help guys, I appreciate it.

Might have a nose around in the members market for a PSU.

HEADRAT