Asrock 970 Extreme3 Rev2.0 wont work properlu with 1+ GPU's

[Nitsi]

Rig:
Asrock 970 Extreme 3 rev2.0
AMD Sempron 145
4GB Kingston DDR3
3x Gigabyte R9 280x OC rev2.0
Win 7 32-bit.
XFX Pro 1250w Black edition

The motherboard detects all 3 GPU's, thats not the problem, but it wont work properly when i have more than 1 GPU installed.
What happens is the rig runs and mines fine for sometime when 3 or 2 GPU's installed then it randomly freezes totally and just stayes in freezed state till restarted.

Tested all parts on another rig i have and they work fine on Asrock 990FX Extreme4 motherboard, so the problem must be in the 970 Extreme3 Rev2.0 motherboard.

Anyone else had this problem or can think of a fix? Tried everything i can think of to fix this, udated all drivers, bios updated, different OS (SMOS, BAMT, Win7 32/64bit), changed card positions, all on powered rises, 1 on riser 2 on pcie x16.

I tried running stress test softwares to see if cards crash on those but they wont, making it impossible to get warranty to replace the board (doubt they run cgminer to do stress tests on send back items), tried taking everysingle powersave option from bios and OS side off but no luck there.

Need help, thanks in advance.

[valkir]

Same problem. Did you find something?

[cescan]

I can't speak to the error right now, but I have started that the eventual plan is to have pathfinding locate and send from the bridge.

[MoneyMorpheus]

Back in 2011 I mined using a sempron cpu. With one card it worked fine. With two cards it was always stuck at 100%. And with three cards it just hanged. I haven't really tried mining with single core cpus anymore, never tested on scrypt, but if you have a dual-core+ lying around I would give it a try...

And also if your mother is unlocking your sempron to a dual-core that might be causing issues.