Computer Won't Turn On

I recently bought a brand new case, and put my old computer into it. Everything seems to be connected right, and when I turned it on everything runs for a split second and turns off. Any suggestions? The motherboard is an ABIT AT7-MAX2. I believe the Power SW and Reset SW are the only ones neccessary, so I took out the LED's until I can figure this out. Both Power SW and Reset SW's were put in the way other friends has told us, but the same problem occurs. Any suggestions?

Thank you,
Ross

 

Powersupply may not be strong enough... unplug things like CD drives and floppy and see if it still does it.

 

The new case came with a 400W power supply, and when everything went wrong I tried my 450W power supply, and the problem was the same.

 

I'll be a bit more specific. Everytime I turn the power supply on, the power led, reset led, thermometer, fans run for .1 seconds and turns right off. as well as this green light on the motherboard that says "d16" lights up green for .1 seconds and turns off. next to that is an orange light that will stay on as long as the power supply is turned on.

 

I think sleepygamer213 was close, but the problem may be at the other end of the power cables.

I suspect that you have a short somewhere, or something that is drawing more current than it should. This also will cause a power supply to shut down rather than destroy itself.

If you've just installed the mobo in the case, check for shorts to ground on the mobo. Make sure that you have non-conductive standoffs if they're needed. (A general rule: if the mounting hole has a solder pad around it, you can use a metal standoff, and probably should. If the circuit board is naked around the mounting hole, use a nylon standoff.)

sleepygamer213's suggestion is still valid: disconnect all peripherals from the motherboard and the power supply except the keyboard, video card and one memory stick. If the system still won't POST, the odds are good you have a short to ground on the motherboard -- or a dead motherboard.

If the system will POST with no peripherals attached, re-install peripherals one at a time until the system fails to POST. The last item installed is probably the defective one. Leave the hard drive till last so that you don't mess it up with constant re-starts. You don't need to boot into an operating system; you only need to see if the system will get past the POST.

 

It might also be the connectors on the power supply, though with two different ones, it's not likely. If you can get a hold of a voltage meter, you might want to check the 12v connections as well. Or simply try switching connections to the device thought to be the problem.

 

Yes, it's possible -- but not likely. A flaky connection would be quite inconsistent about how long it let the system run -- if it let any power through at all.

 

I recently had a similar problem with my Abit mobo. It turns out my new Zalman heat sink was not covering the entire CPU. Is your hs on good? Try the mobo on the cardboard trick to help find the problem. Worked for me.

 

Hmmm. I didn't think of that possibility.

But what's the "mobo on the cardboard" trick? I hadn't heard of that one. Could you spell it out for us?

 

The mobo on the cardboard trick: take out the mobo and put it on a non-conductive surface (i use a flattened cardboard box), install only the essentials (cpu/w heatsink and fan, a stick of ram, vidieo card), make all the connections and power it up. It should help you eliminate possible problems like a short on the case.

 

Yea some people call that their TRUE desktop setup (the pce is sitting on their desktop without a case) Some call it the open air setup, some call it a bare setup etc etc...

Anyways, that is another possibility.. Your CPU may overheating causing a restart... When you hit the power button does it just flash on once then stop or does it keep doing it?

This is beginning to look more and more like a PSU problem to me.

Hehe, Rob M. is the almighty master of PSU's... Or maybe its just because he has that book

 

well i tried the cardboard trick, and it still doesn't work.

" When everything is connected outside of the computer case, I turn the power supply on and all the fans run as well as motherboard lights. Exactly .1 second later it all turns off. "

 

Presumably, you had it down to the basics on the cardboard: mobo, CPU, video adapter and minimum memory -- and the PSU to power it all. Nothing more.

It still won't stay powered up. Well, I think you can be pretty certain it's one of the five items above -- including the PSU. Which one of those parts? Time to start swapping those parts out one at a time.

My wife's office computer once behaved as you described. Turned out it was a shorted modem. I replaced the modem, and everything was fine. I never did find the short in the modem or what killed it. -- but I didn't look very hard. They're not usually fixable.

 

It might be your power supply, You might want to go to a computer parts store that you trust and get a generic (non brand name ,there cheaper priced) power supply and see if that works.

 

The problem has to be with one of the connections you removed during the transplant,unplug everything again and reconnect outside the case,also reset the cmos jumper or remove the battery for 5 secs