I have a computer that i built over summer around june. up until today it was working very well. I went to turn on my computer and the unit turned on for about a second and turned off. I took the case off, unplugged one of the fans and turned the computer on, started fine. i turned it off, plugged the fan back in and it ran for about 3hrs before suddenly turning off. i tried to do the same thing (unplug one of the fans) and when that didnt work i continued to unplug other components to no avail. i plugged everything back in and now its just sitting on my desk.

heres all the hardware im running:

Maxtor DiamondMax 21 STM3320820AS 320GB 7200 RPM SATA 3.0Gb/s Hard Drive - OEM

Intel Core 2 Duo E6300 Conroe 1.86GHz LGA 775 Processor Model BX80557E6300 - Retail

GIGABYTE GA-945GZM-S2 LGA 775 Intel 945GZ Micro ATX Intel Motherboard - Retail

WINTEC AMPO 2GB (2 x 1GB) 240-Pin DDR2 SDRAM DDR2 667 (PC2 5300) Dual Channel Kit Desktop Memory Model 3AMD2667-2G2K-R - Retail

LITE-ON 18X DVD±R DVD Burner With 12X DVD-RAM Write Black IDE Model LH-18A1P-186 - Retail

APEVIA X-QPACK-NW-BK/420 Black Aluminum 1.0 w/ ABS plastic front panel MicroATX Desktop Computer Case 420W Power Supply - Retail

i added two more fans and a geforce 8600gt video card.

is there a possibility that my power supply is shot?

List your power supply specs.

Power Supply specs:

Specifications:
Intel Pentium 4 support
SATA support
Wire sleeves on all wires
AC Input: 115V/230V~ 10/5A 50-60Hz
DC Output: 18A@+3.3V; 22A@5V; 20A@12V; .3A@-5V; .8A@-12V; 2.0A@+5VSB

http://www.directron.com/as420w.html