Pretty Much my computer wont start, only the Fans will start then it shuts down, I have to keep unplugging the power cord and replugging it back it for it to try and start up again. after about 30 tries my PC will Finally start up and stay Running just fine. When I get it Running I can shut it off and turn it back on with no problem, But if the PC is off for a hole day, its a pain to start.. This Computer was my 1st build, and its worked great until now, I built it about 4 months ago.
The power supply is my old silverstone 650watt I had in my last PC. I'm using it until I can buy a 750watt power supply.
specs to computer.
Processor: AMD Athlon II X4 630 Processor (4 CPUs), OC'd 3.2GHz
Memory: OCZ AMD black edition 4096MB DDR3 1600
Hard Drive: 750 GB and a 1TB for games/music
Video Card: XFX 5870 1GB Eyefinty overclocked.
Sound Card: Creative sound blaster X-Fi
Operating System: Windows 7 Ultimate 64-bit
Motherboard: ASUS EVO/U23S6 SLI, USB 3.0
Well, it could definitely be the PSU. Just FYI, you only need to hit the little switch where you're plugging the cable into the PSU to disable the power. I'd recommend you try a different PSU in there first. If you can buy one locally with a return policy, then that'd be great just get a good one and then see if it works. 650W should be fine for that PC but if it's older, it could be at the end of it's life for sure.
Just for a test, pop open the case and reset the CMOS (you'll lose your OC settings).
Breadboard with just motherboard, CPU & HSF, case speaker, and PSU.
Make sure you plug the CPU power cable in. The system will not boot without it.
I always breadboard a new build. It takes only a few minutes, and you know you are putting good parts in the case.
You can turn on the PC by momentarily shorting the two pins that the case power switch goes to. You should hear a series of long, single beeps indicating memory problems. Silence indicates a problem with (in most likely order) the PSU, motherboard, or CPU. Remember, at this time, you do not have a graphics card installed so the load on your PSU will be reduced.
If no beeps: Running fans and drives and motherboard LED's do not necessarily indicate a good PSU. In the absence of a single short beep, they also do not indicate that the system is booting.
At this point, you can sort of check the PSU. Try to borrow a known good PSU of around 550 - 600 watts. That will power just about any system with a single GPU. If you cannot do that, use a DMM to measure the voltages. Measure between the colored wires and either chassis ground or the black wires. Yellow wires should be 12 volts. Red wires: +5 volts, orange wires: +3.3 volts, blue wire : -12 volts, violet wire: 5 volts always on. Tolerances are +/- 5% except for the -12 volts which is +/- 10%.
The gray wire is really important. It should go from 0 to +5 volts when you turn the PSU on with the case switch. CPU needs this signal to boot.
This checks the PSU under no load conditions, so it is not completely reliable. But if it can not pass this, it is dead. Then repeat the checks with the PSU plugged into the computer to put a load on the PSU.
If the system beeps:
If it looks like the PSU is good, install a memory stick. Boot. Beep pattern should change to one long and several short beeps indicating a missing graphics card.
Silence or long single beeps indicate a problem with the memory.
Insert the video card and connect any necessary PCIe power connectors. Boot. At this point, the system should POST successfully (a single short beep). Notice that you do not need keyboard, mouse, monitor, or drives to successfully POST.
Now start connecting the rest of the devices starting with the monitor, then keyboard and mouse, then the rest of the devices, testing after each step. It's possible that you can pass the POST with a defective video card. The POST routines can only check the video interface. It cannot check the internal parts of the video card.
^One problem... it seems motherboards don't come with speakers anymore. At least, my two P55 mobos didn't (MSI and ASUS)
EDIT: I know that may not apply to him, I just find it rather stupid and frustrating.
if it doesnt work after being off for a full day it sounds like a bad capacitor. Once they get old/leaky, they can work fine until power is lost, then they have problems. The PSU is out of warranty, so you could take the cover off and have a look for bulging/leaky caps (unplug from mains first and dont touch anything in there to avoid electric shock.) That would be the first thing I would do, so simple, so quick.