I've just got myself a 8800GTX (hasn't arrived yet though). My PSU (Tagan) is 480W.
Before getting myself a stronger one I want to give it a go just to see what happens. Is that a good idea or can I blow the PSU by doing this?
Is there a way I can tell that there's trouble ahead while the computer is on and I'm playing a game, say?
From a bit of research, I see that that PSU has 28A (336W) on the 12V rail. The GTX uses about 11A, so you got 17A left. A C2D e6600 (you didnt specify your CPU, so I am pulling a common one out of the air) uses about 4.6A, so thats down to 12.4A. The rest of your system has (to be safe) 10-10.5A left over to run off. A typical SATA hard drive will use around 2A and a DVD burner running at full power uses around 1-1.5A (but only when reading or writing), so if you run more than one, that will hurt also. You should theoretically be able to run it, since you have a single rail PSU, but it would be cutting it close if you have more than one HDD or run an old pentium or a C2Q.
EDIT: List all your specs and that will make it easier to work out how much power you are going to need.
Would I experience a very distinctive lack of performance in that case, or could a lack of power go unnoticed? I will be running games to push the card to the limit (Bioshock at 1920x1200)...
Believe me if it clocks down you'll know, yes you would notice a very distinctive lack of performance. Your PC might even reboot or turn itself off because a lack of power. I have never heard of a case where having a not enough power caused damage.
Ok, I just stuck it in (and what a big one it is!), fired it up, all seems to work ok. Bioshock framerates still not great (at 1920x1200, ah well), 3DMark06 somewhere around 9000, which is average I suppose.
So, everything seems to be working just fine. Guess I'm lucky!
No no! I'm running BIOSHOCK at 1920x1200. 3DMark is the standard free edition.
I've just installed the latest Beta Geforce drivers, and now I get very good framrates in Bioshock as well (around 50-70), so I'm very happy, really...
You can use this site to calculate your power requirements. It is always better to use the actual power consumption figures from the hardware you have though. This site gives an acceptable range figure. Always add 20% safety margin to their figures. You do not want to running at 100% of your power capacity.