I own a Sapphire X1950 Pro AGP 512MB. It's one of the rev1 boards, I got it back in december 06.
First thing I had to do was toss out the crap 400W psu and shove in an Antec Truepower Trio 650W. The trio means 3 high-Amp 12V rails. Perfect
I too have had a lot of troubles with the screen going black after heavily loading the card, from anywhere between 5 minutes to sometimes 30 minutes of playtime.
When the screen'd go black ( as in no signal), even pressing the reset button didn't help, I had to completely turn off the system before I'd get the display up again. Only rarely did the only the game crash and did it rtd.
After a wile, I upgraded. Although the cooler sounds infinitely cool - it sounds like an F16 getting ready for take-off - it annoyed the hell outta me. Up to the point that I switched to watercooling. Not just for sound, also overclockability. I have a waterblock on the GPU
and the gpu RAM.
Unfortunately, this didn't improve stability, nor did I get more overclocking headroom.
( apart from the CPU that is)
But browsing these fora and extremeoverclocking.com provided the answer.
2 things I changed;
one guy suggested setting AGP to 4x and disabling Fast Write ( this is done in CCC)
The other thing is get some cooling for the VRMs ( I have the teeny tiny versions)
I got some very small blocks (pathetically small to be honest, I never thought they'd make any difference) for the 3 vrm's, putting me back a whopping 1€( that's like 3 US$
) . Today, after playing Bioshock for 6 hours ( girlfriend is still mad at me
) I never once got the black screen. Not only that, before I only got 621/721 ( as opposed to the 580/700 default clocks) overclocking without the game crashing before games even loaded. Today, so far, the card has been running at 635/755. No artefacting, no crashes. The card never goes over 50 degrees. When in 2D the card switches back to stock clock speeds and it idles at about 37. I run Bioshock at 1280x1024 with ALL details enabled. Always smoooooth as a baby's - let's not go there.
I'm sure I can get higher clocks, I 'playtested' long enough yesterday with the above specs. Temps are not an issue, so hoping it can take 650/7??. I'll try later today. ( and post the results if anyone gives a frag)
Oh and I use Ati Tray Tool, latest version for the OC'ing bit. ATI drivers are also the latest version ( 7.10?)
So, I feel it is my duty to pass on my experience;
anyone with a Rev.1 card, cool the VRMs and/or downgrade the agp port.
Update; still running free of probs at 654/772. I'll post the 3DMark06 scores as soon as my ISP gets their act together and I can access the online results.