I just installed a second video card (GeForce 7900 series) alongside my older GeForce 6700 Series. After the computer was powered on for about a day, I came back to find the unit dead, with the power button not responding at all. After changing the plug from a power strip to a different wall socket, it seemed to partially power on, with these results:
- Two of the three case fans were operational
- The motherboard's green LED was on
- The GeForce 6700's fan was operational
- The DVD drive made standard bootup sounds
However, the CPU fan was not on, one case fan was not on, and the GeForce 7900's fans were not operating. Additionally, after pressing the power button to turn the computer on, it could not be turned off by anything except flicking the PSU's power switch.
Here are the machine specs:
- Rosewill Capstone-650 (650 watt power supply)
- Asus P8B75-V motherboard
- Two graphics cards (as described)
I removed both video cards, but nothing changed. I have a strong feeling I fried some combination of the motherboard, the PSU, and possibly the graphics cards – possibly because my PSU wasn't powerful enough to handle the load. Can anyone shed any insight on this?
Best Answer
Most likely it's the power supply.
The video cards can draw a lot of current from the 12V rails. Some of the cheaper power supplies with lower wattage ratings can't do it, especially on a 2 card setup like you have. So I'd start by looking there. First remove all the cards and see if the motherboard powers on (that'll verify a card hasn't come loose and is shorting the pci-x bus).
If not, have a look at one of the many howto's on the web for testing your power supply. e.g. http://pcsupport.about.com/od/toolsofthetrade/f/powersupplytest.htm If you don't have a tester, then open it up and check fuses. See below:
Personally, I think 650W is too low for a 2 card setup (particularly those cards. They are toward the high end of current draw). You should have at least 800W or above. For a 3 card setup, 1200W+ is recommended.
I should add that most power supplies have overload or short circuit protection. See: http://en.wikipedia.org/wiki/Power_supply
If your PSU appears to be dead. Carefully remove the screws (CAUTION! High Voltage - be very careful what you touch). You may see some fuses inside. Are they still intact? If they are not then it's what's likely happened is that too much current was drawn and the fuses popped. Then you can replace the fuse and use the PSU in another machine. Now go out and buy a higher wattage PSU!