Computer won't boot up inside case, but wil outside

So I bought all the parts to build a new computer.
Slapped the bad boy together, tried to turn it on, NOTHING.
No lights, no fans, no noise.

Troubleshooted for awhile, Figured out that maybe it was the power switch on the new case. So I decided to put it into another case. It booted up just fine, ran it all night. No problems what so ever.

So I really want to use this new case. And thought that maybe I would try the reset switch plug in on the power plug in on the motherboard that's in the OLD case. Boots up just fine. So I think to myself ok great, so I'll just use the reset button as the power button no big deal.
Ummm..no, didn't work out that way.

So I plug everything back into the NEW case, use the reset switch plug on the power pins on the motherboard. NOPE. Same thing as before, won't boot up at all, no fans no lights nothing.

So at this point I'm pretty steamed So I pull everything out of the new case, and put it on a piece of cardboard, plug everything in the way it's suppose to be. Only thing I have are the ram, cpu/heatsink in the unit.
IT TURNS ON!!!!!

So everything runs fine placed into a different case, runs fine outside of the case, but will not run in the case. The only thing I can think of is something inside the case is shorting it out.

What could be causing this?

Thanks for any help.

try taking the power button out of the old case and into the new one (the internal button) it may just be a bad switch.

Hi,

I know this sounds obvious but.......

Make sure the brass standoffs between the motherboard and the case are only screwed into the case where they line up with the holes in the motherboard as to not cause any shorts against the bottom of the motherboard.

Same power supply when it works and when it doesn't?
Nothing added or different when it is in the case from when it is one the table and working?

One thing I'm sure of it will be something simple.

Good Luck
Roger

1. Test the AC Input Voltage to the power supply using a meter
2. Test the DC power output from the power supply using a meter
3. Whilst mother board is out side the case flex the mother board to see if it will still boot whilst flexed.
4. If all correct
5. Place the mother board in the case but not fixed i.e. free floating and insulated from everything
6. Connect up the mother board
7. Test the mother board Voltages using a meter.
8. Will it boot? => Check the mother board for cracks
9. If it boots
10. Apply one attaching screw/device at a time testing to see if it boots after each attachment is made.
11. If after applying a connector and boot fails examine the board and connector to see what is damaged/shorted

Problem is either 1. power supply voltage, 2. Cracked Mother Board 3. Short when screwing/attaching mother board to case.
If mother board is cracked just plugging a cable in whilst holding the board in it's case will open up the crack.

Moderator edit: This topic is three months old.

Two obvious causes, something is shorting the board or the power switch isn't working. Standoffs that aren't all there or properly seated could cause this.

Old topic, but it came up high in my Google search yesterday.  So I though this would be helpful. 

 

 

I had the same problem, computer would boot then 4 seconds later shutdown. But outside case with nothing plugged but PSU, and memory sticks runs normally. 

 

I discover by chance my problem: the Power on switch partially faulted in the on position.!!

 

Never saw it during my search on the web, so I just want to help the next victim.

 

An easy test : unplug the power on switch, short the 2 pin on the motherboard to start the computer. 

 

Using the reset switch for the time being, until the new switch arrives.

 

3 years old case, Gigabyte 770t-usb3  AM3 motheboard.