A little background -- I'm assembling a 6 computer gaming LAN and came across some IBM NetVista mini towers with 2.66GHz P4 CPUs, 4x AGP, and 185W PSUs. They were $60 a pop and included a WinXP Pro COA so I couldn't resist! It wasn't my initial plan to totally pimp these systems out with a decent video cards (well, decent as far as AGP is concerned!) until I realized that with beefier video cards I could run COD4 pretty well, in addition to some other pretty fun games that aren't very compelling, if even runable, with a Radeon 9xxx class video card.
I ended up selecting the Sapphire Radeon X1650 512MB 4x/8x AGP video card as NewEgg has a pretty good deal on them for around $50 a pop. After buying a bunch I realized that the power supply might be a problem. I see that a 350W PSU is recommended for that video card. Though after doing some research I learned that the total wattage of a PSU isn't really what's key when it comes to adding a power-hungry video card. Rather, it's the allowable amps on the 12V rail that matter because the 12V rail already has lots of hardware on it -- like the CPU, hard drive, optical drive, etc.
The 12V rail on the 185W PSU in these NetVistas is rated for 10A. I'm running a P4 2.66GHz CPU (Northwood, I believe), 1GB of RAM (512MB DDR modules x2), 40GB hard drive, onboard audio, onboard 100MBps NIC, DVD-ROM drive, and there's a 80mm system fan. I used a Kill-a-Watt to measure the Watts used by the whole system with the Radeon X1650 installed and running the COD4 demo, as well as some other games with the graphics cranked up, and it pretty much peaked at around 150W (the whole system). Assuming most of the power usage was on the 12V rail, that's 12.5A. Granted, not all of that power is being used on the 12V rail, so perhaps that 12.5A figure is a little less, maybe 11A or 10.5A?
My question is what should I do? I didn't notice any instability after testing this configuration for an hour. Of course, an hour is different than 6 hours, like the kind of usage it might get during a LAN party. That model of NetVista uses what appears to be a micro ATX PSU, so even if I upgrade the PSUs on the systems, I'm pretty limited in my options and mATX PSUs are more expensive. I'm not too enthusiastic to modify the case for a standard form factor PSU, but who knows. The mATX PSUs with 20A on the 12V rail are around $50 to $60. I see some that are 12A or 16A on the 12V rail for a little less -- maybe around $30-$40 each. What risk do I run with using the stock 185W PSU? Damage to the PSU? Damage to the video card? Damage to the computer? System instability? Fire hazard? All of the above?
Then there's part of me that wants to scrap this project as I don't want to risk damaging $300 in video cards and $360 worth of computers I've purchased. Of course, when I see how sweet a game like Flatout 2 looks on this setup compated to the GeForce 6200 and Radeon 9600 I had in there before, maybe getting better PSUs would be worth it. Thoughts? Recommendations? Thanks!
If Kill-A-Watt say 150W at idle, at load it would be another story.
If you run a computer on an underpowered PSU, you risk that PSU destroying your entire investment. That's why we recommend not skimping on the power supply.
Stay away from generic PSUs also. They tend to destroy computers.