Help requested - video signal disappearing!

Hi all,

I wonder if anybody can help me.

The last week or two I have started having problems with the video
output on my PC.

I am running a clone P4/2,53Ghz 533FSB with 512Mb Rambus, Geforce Ti4600
dual head (1 x VGA and 1 x DVI) - running one monitor off each head.

What has been happening is that, for the most part, it appears that the
video signal itself just disappears for a second or two (long enough for
the power save messages to turn up on the monitors) and then it flicks
back on again. PC operations continue as normal.

On say, 1 time out of 10, the screens either blink on or off repeatedly
(on for say 3 secs, off for 1) or the screens stay off - go into sleep
mode and my then PC reboots. Nice

Running dual monitors is handy here as the problem affects then both at
the same time - both monitors react as if the VGA cable has been yanked
out the back. So I think this rules out the monitors.

It *seems* to happen more when I play a 3D game (although not all of the
time) that rather suggested a heat issue. So today I've had the GeForce
out, cleared all the dust from it's fans / heatsinks etc. and re-seated
it. Sadly, the problem persists. The GPU fan seems to be working as it
should - as does all of the other fans in the PC.

Gut feel is the video card - the bit that makes the signal (no idea what
it is called - digital to analogue converter?). I would be very grateful
for any other experiences or suggestions.

System has been stable in it's current configuration for at least 12
months - running latest drivers - problem occurs on latest WHQL
certified ones and also with latest Forceware (non-WHQL certified) from
nVidia. Running XP SP2 - ran fine with SP2 since day 1 of release -
problem started happening over the last week or so.

Many thanks for any guidance before I shell out on a new graphics card.

--
Steve