Just a quick post to let you guys know my experiences with the 4870 X2.

The cards run extremely hot, around 85C when idle. The temperatures used to be lower when I was running Catalyst 8.7 with the 4870 X2 hotfix, but since 8.8 the temperatures have gone up.

There also doesn't seem to be an easy way to manually adjust the fan speed, and after following several tutorials on the Internet about editing XML profiles, these haven't done anything either. There is an application called EXPERTool which can successfully change the speed of one of the 4870 X2's, but doesn't work on both cards! So one ends up spinning at 100% and the other stays at 27% for example...

Also, the driver has caused several blue screen error messages (driver got stuck in an infinite loop message) and system crashes and restarts when playing a few games. There are problem applications that always crash - Crysis Demo is one of them (it will get stuck on the intro movie so you have to skip it), and Unreal Tournament 3 in Campaign Mode only... Instant Action is fine and you can play for hours on end.

So, all is not rosy with the 4870 X2. However, I can confirm that when the game works, it works phenomenally. There is nothing out there than can outperform this incredible quadfire setup when given the right application. Crysis Demo runs very well... Team Fortress 2 runs very well... Counterstrike: Source Video Stress Test averages at 294.04fps!

Update: I'll upload a video to YouTube at some point to show you what happens in Unreal Tournament 3 campaign mode.

Awesome but buggy? Sounds about right for an X2 card, especially one in crossfire.

Yes, also because there are very few people out there with this 'quadfire' setup it's very difficult to get other peoples experiences, because they generally only have one of these cards, or two 4870's in Crossfire.

what about 9800 gx2 and 3870 x2?

They are old

OK so I have found out what causes the problem most of the time...

If a game starts in windowed mode or if a game goes from 3D mode to windowed mode, then returns to full-screen mode, it does not seem to like that very much and I will get either a BSOD or a system restart or lockup shortly after. This has happened in Crysis single player demo, Unreal Tournament 3 and Call of Duty 4 single player demo so far...

Perhaps a problem with the driver adjusting the clock speeds and loading game profiles etc. ? Who knows... I just hope my problems will be fixed in Catalyst 8.9.