Need help

[TankGrater]

Ok, so first off, here are my system specs:

i7 920 Quad core
Cooler Master V8 180w cpu heatsink/fan
12GB Triple Channel G.Skill PC3 10666 (6x2GB)
Gigabyte GA-EX58-EXTREME motherboard
Samsung SyncMaster Touch of Color T220 LCD monitor
2 650GB seagate sataii drives in raid0
XCLIO Windtunnel Fully Black Finish 1.0 mm SECC Chassis ATX Full Tower Computer Case
CORSAIR CMPSU-750TX 750W ATX12V v2.2 SLI Certified CrossFire Ready 80 PLUS Certified Active PFC Compatible with Core i7 Power Supply
Windows Vista Ultimate 64bit
cd/dvd burner

Windows update is current, newest drivers etc.

And, here is the problem:

I recently purchased two GIGABYTE GV-R687OC-1GD Radeon HD 6870 1GB 256-bit GDDR5 PCI Express 2.1 x16 HDCP Ready CrossFireX Support Video Card with Eyefinity from newegg to replace my one ASUS EAH4870 DK edition GDDR5 1GB card. The cards arrived, I installed them with the latest drivers from manufacturer's website. Both cards are detected, no problems flashing on my screen, everything appears good, crossfire enabled flawlessly via catalyst. Then I try to run games; It will play games for about 2 - 3 minutes then all of a sudden the video "shuts off" leaving a No Signal message bouncing around my screen. I still hear audio coming from my speakers, but the only way to recover is to force shut off by holding in my case power button and turning it on again. This happens with any game...spiral knights, witcher 2...even happens with heroes of might & magic kingdoms webgame. The cards are seated properly, both have the 2 6 pin connectors plugged in(straight from the PSU, the power adapters were not needed), crossfire bridge. This problem happened before I installed the cpu cooler, was running on the stock cooler provided with my cpu until today. I have tried the drivers directly from amd's site as well but they were not stable.

Note this string:

http://forum.giga-byte.co.uk/index.php/topic,3892.0.html

Apparently I'm one of many that are having this problem, and google searches are not bearing any solutions. So...

Could it simply be that my $120 750W PSU is not adequate for running these 2 cards? It says "Crossfire Ready" but the exact model is not listed in the "crossfire certified" list (the plain TX750W is but I don't see the CMPSU one for 750). Is it a design flaw/driver error that gigabyte has not yet corrected? I'd rather not play the RMA game if possible. If more info is needed please ask and I will try to supply.

 

[orangegator]

Did you even read the thread you linked? It apparently is a flaw with the voltage regulators used in some cards. Your options are to rma the cards and hope they send you a working one (not guaranteed from what I read) or return the cards for a refund and buy a different model. I suggest getting a 6950 2gb

 

[TankGrater]

Yeah, that was mentioned, along with many other speculations. Does anyone here know the real skinny on this? If I were to send them back for a refund, does anyone have any recommendations on exact manufacturers/models to aim for or stay away from? I'd like to not bump into this again.