Thanks very much for the responses and suggestions.
I'm using a GeForce 8600GT card at the moment, so my system tells me.
I'm pretty sure it's not the cooling issue. We upgraded the cooling quite a while ago - it was the first thing we tried, but it didn't have any effect. Anyway, I get problems right from the start, booting from cold. It's not consistent either. Sometimes I boot and it's absolutely rock solid, no matter what. Other times, I boot and the graphics corrupt after a few turns of the game.
The "fix" (sort of) is to save, tab out to Windows and then go back into the game. But when it's really bad, it will corrupt almost every turn, making things *unbelievably* tedious
And then, very infrequently but too frequently for comfort in a Time game, it crashes instead of just corrupting, the whole system freezes and I am invited to report a serious system failure to Microsoft when I reboot
With this latest card I do typically get some warning that it's about to crash completely - a 5 second pause, then the corruption and then I get the cursor back. Generally time to save, quit and reboot! That's an improvement on my last card. No warning at all with that one ...
The other strange thing is that it is at its worst in the early stages of the game. The more it has to do, the more stable it is, so later in the game it's maybe corrupting every 30 minutes to an hour or so, which is tolerable (by comparison, at least!) It also seems to be true that the longer it's running in Civ, the more stable it gets, regardless of map size.
I haven't switched my computer off for five days now, because it has been rock solid and I just don't want to risk rebooting
Honestly, it's that bad. So I'm sure it can't be that it's getting too hot - surely it would be in meltdown after 5 days if that were the case?
The power supply thing is interesting. I mentioned this to in-house systems a while ago, but he assures me that I have more than sufficient power. Sometimes, though, I wonder whether he forgets to add the phrase "in my opinion and anyway I'm too busy to look at it now"
He built the system and swears it's correctly specified. I will talk to him about it again though, given your comments. Thanks for taking the time to write all the detailed info on this Sun Tzu Wu! Much appreciated.
With power supply problems, are they sometimes intermittent in the way I'm describing? That's what gets me. Why would it be perfect on some boots and absolutely *dire* on others???
From an ecological point of view, I'm going to have to turn the PC off. But I'm dreading it ...