5850 crossfire setup crashes under load

[leumasshake]

So I've had a MSI 5850 Twin Frozr II for a while now and been very happy with it overall. I just bought a second 5850 to run in crossfire, an XFX. I moved the MSI card to the third slot and installed the XFX in the first slot. I reinstalled catalyst 12.6 and everything appeared to be working just fine. I was able to read the temps and all other data in afterburner for both cards. Both cards were sitting in the upper 30s C, a bit warmer than I'd like, but to be expected running crossfire. I was curious just how hot the cards would get now so I loaded up Kombustor and the comp instantly restarted. No blue screen, no error message, not even a single frame shown in kombustor. It all just disappeared immediately. I have repeated this several times now with the cards and crossfire bridges in different configurations but get the same result each time. I have no idea what could be causing this. I have a 730 watt PSU which leaves plenty of headroom, so I don't think its a power problem.

When windows loads again, it is in a lowered resolution with no option for 1680x1050, and CCC can't open. Get an error message saying "there are no settings that can be configured by catalyst." I have to uninstall then reinstall catalyst to get it working again.

I also noticed as soon as I connected a second card the computer took much longer to boot up. I have a crucial m4 ssd, used to boot up in about 30 seconds or less, but ever since i connected the second card its taken well over 5 minutes each time.

Has anyone here seen something like this before? No idea if these two problems are even remotely related, but I thought it would be helpful to give as much info as I could.


System specs:
i7 920 @ 3.8Ghz
MSI x58 Pro-E
6GB DDR3 1600 RAM
2x Radeon 5850

 

[leumasshake]

Update:
I've now tested the new card (XFX) on its own, not in crossfire. It doesn't immediately crash when kombustor loads, but it does get up to about 90C in about 2 or 3 minutes before I stop it. The card has an accelero twin turbo cooler on it so this is absurd how hot it is getting. It idles at about 33C. I just replaced the thermal compound with arctic silver 5 and had similar results. I didn't really expect that to fix it as the old compound seemed to have a very good contact. I don't understand how this cooler is so ineffective.