Mitt X1950 PRO och dess problem, hjälp uppskattas!

Hej, jag har väldiga problem med mitt X1950 PRO i nya spel. Skulle verkligen uppskatta om kunnig kunde ta sig tid att kika på problemet =).
Ni får ursäkta att inlägget är på engelska, men har postat det på lite olika ställen, för större möjlighet att få svar.

Tack på förhand
/Johan

Hello, my name is Johan and I own a X1950 PRO.

This is my Setup:
SAPPHIRE RADEON X1950PRO 256MB DVI PCI-E (Driver 7-3_xp_dd_ccc_wdm_enu_43737.exe)
MSI K8N-NEO-4F NFORCE4 SKT939 STD ATX
AMD Opteron 144, 64bit
Windows XP Pro, SP2, Latest DX9, Latest motherboard and sound drivers.

For the X1950 PRO: "The most important requirements of them are those to the power supply unit ? at least 450 W which provides at least 30 A current over the 12 V line."
Because of that I have PSU: Aspire Chameleon ATX-AS550W (550W) 36A over the +12V (peak 38A)

My problem:
Up until recently I have been playing older games with this setup, such as EVE-Online, CS1.6, WC3:TFT etc. It functions perfectly at the highest settings (with all extra filterings etc enabled). I have now begun playing newer more advanced games in terms of graphics. What I encounter doing this, is not pleasant...!

Need for speed: Carbon, FlatOut2, S.T.A.L.K.E.R, Test Drive Unlimited, Dreamfall: The Longest Journey, Command & Conquer: Tiberium Wars, are some of the games I play, (all in all I play most new games...)

What happens is that all of these games crashes in a few very specific ways, when the graphics card starts to work a little more (I can hear it is when the fan begins to speed up). Either the monitor looses its signal, or everything hangs (with the sound repeating). Other crashes include reboot. One time I shortly saw some artefacts after the picture went black. In one of these cases the computer boots but without any signal for the monitor.

I can direct how long it plays before the crash by adjusting the graphics in different ways. The higher the graphics, the sooner it will crash. I have tested to adjust the games own settings with the card at factory defaults, and the card at different settings.

As i up the Ansiostrophic (both ingame and/or with the CCC), games are immediately more likley to crash...

The problem becomes more common. Today it takes only a few minutes at best graphics setting for it to crash.
The number of frames per second are never effected...
If i play with low settings, it takes longer, but it will always crash...

What could be the problem? Heat? (I have a thermaltake chassis, with alot of fans for a contant airflow.) The cooling solution for the card might not be sufficient?
PSU? Well my PSU is above what is required. The PSU is developing alot of heat, but I guess that is normal.
Drivers? I have the latest... for everything.
The card itself in terms of hardware? Likley, yes.
The card compatibility in terms of software? Likley yes.

Or what can it be =(? I am constantly thinking "oh no it might crash soon"... It destroys the gaming experience...
Thx in advance for help!
/Johan

Det hade helt med värme att göra, problemet är nu åtgärdat!