My problem is this:
I just bought a new video card and a new power supply to go along with it. The card is a Sapphire X1950GT 256MB AGP (http://www.newegg.com/Product/Product.asp?Item=N82E1681...) and the psu is a 500W Rosewill (http://www.newegg.com/Product/Product.asp?Item=N82E1681...). I thought the psu would be powerful enough for the card, but I calculated the required ameperage incorrectly and now I'm not sure it's enough. The psu has 2 12V rails, with 15A on the first, and 16A on the second. The box lists 350W across the two 12V rails, for 350/12 = 29.16666A on both rails (Don't look at the stats on Rosewill's product listing, it incorrectly lists the amperage at 20/18A). Is this the correct way to calculate the amperage? The card calls for at least 30A, but mine is less than 1 Amp below that. I have a 2.66GHz P4 chip, a CD-R drive, a DVD-CD drive, and an IDE hard drive also being powered by the psu. I put the video card on one power cord, and the other drives on the other. Is that the correct setup? I'm new to psu issues, and this is the first time I've had to deal with it before.
Here's what makes this frustrating for me though. When I first got the card, I installed it and booted the computer with my new lcd monitor. It worked beautifully for about 5 minutes, then the signal died completely. There was nothing coming out of the card, and the monitor quickly went into standby (also indicating no signal). I took the 1950 out and reinstalled my old GeForce. The computer runs fine when I put the old card in, but won't display anything with the new one. I also tried my old crt monitor, it also got nothing.
The other wierd thing is that when I plug in the computer with the old card, I have to turn on the computer's power button on the front to turn it on, just like normal. When the 1950 is installed, the computer powers on as soon as I plug it in, it doesn't wait for me to turn it on. The only way to turn it off is to unplug it. Everything runs, HD, fans, even the fan on the 1950. That to me says that there's a fault in the power, since the psu's manual says that when there's a fault, it will power on until the fault is corrected (I'm paraphrasing, I don't have the manual with me). So, the card seems to be causing a power fault, does it sound like the card's fried? Since it ran for a few minutes before dying, could the power have been insufficent for more than that long, and killed it? I tried uninstalling the GeForce drivers and installing the 1950's drivers, but no luck. Any other ideas I can try before calling Sapphire's tech support? Any details I've left out? I've tried to lay out the problem as well as I could, if anything isn't clear, let me know.
I got the card to work again for a while. I downloaded the drivers from ati's website and installed those. I had previously installed the driver from the cd that came with the card. I also unplugged the cd, dvd, and floppy drives. It worked fine for everything I did on the desktop. To tax it a little bit, I launched Oblivion with Medium graphics. It worked fine when I was inside a building or inside the city, but when I went out to the world, the screen turned to green squares, and the card died. I've decided to return the psu to newegg and order a more powerful unit.
Thanks to everyone who read this. I'll post again when I get it working, in case anyone else has the same problem.
Is the card overclocked at all? I have a his card that was overclocked from the factory. I didn't buy it for the overclock but for the way it exhausted the air out of the case. I was getting artifacts and such when playing higher end games. Dropped the speeds back closer to stock and its been fine ever since. I got a 650 watt thinking power was the problem but it was just the overclock.