When I set my video settings to 32bit my PC trips out and restarts...

[monkeystu]

This is a bit of a strange one.
I have bought (for a few pounds) a peculiar PC from my work that wasn't being used and was said to be broken.
It looks like a giant black heatsink. There are no moving parts except for the HDD and all the cooling is done by heatpipes to the "very heavy" aluminum case. (This thing has wheels it's so heavy.) However I knew that it was a reasonable powerful machine and that it was bought more as a demonstration of heatpipe technology (by a, now retired, eccentric Manager) rather than a working machine. I have been meaning to set up a home music studio and thought that this thing would be great as there is no hum or fan noise to spoil the recordings.
Anyway, I rebuilt it and found some loose screws and power cables and found out that if you close the door (yes it has doors, two of them) on this thing that it presses on the mains power cable.
So I fixed these problems put in a new HDD and it worked fine. I left it on for days and ran as many pieces of software I could find and it seems to be OK.
I only had a very small old monitor for it, so I bought a nice 22" TFT with DVI monitor for it the other day. I hooked it up and it seemed to be OK, until I tried to set the resolution. The monitor needs 1600 x 1050 (or something close to that). It would deal with that, but when I tried to set the colour to 32bit rather than 16bit and pressed apply it trips out the computer, and restarts.
My theory is that the AGP video card is demanding too much power from the main board when the 32bit is selected which in turn trips out the powersupply.
What do you think?
Stu.