a m8 just been to see me his pc keeps shutting down he said all he’s changed is the fan on the cpu . now when ever he starts his pc as soon as it gets turned on it shuts down again after about 2 seconds no beeps or sounds from the mobo or anything
please help …lol
many thanks all 
brucie
Hmm, has he gone from a 3-pin fan to a 4-pin molex connector on the fan? The motherboard could be set to shutdown if it doesn’t detect life on the cpu-fan header.
problem solved 
he knaffed the mobo up short circuit
No beeps hmm?
First I would check all the connectors from the power supply are correctly fitted. If any were removed to fit the new fan they may not be put back properly. Normally there should be no spare power sockets on the mobo. A classic one is to forget the 12v square black and yellow plug.
If all is present and correct, but still no boot, make sure the power supply fan and/or heatsink fan is turning even for a couple of seconds on power up.
If they are, then it’s time to have a steady hand and a well earthed bench… the cpu may not be correctly fitted or may have been disturbed when the new fan was fitted.
Turn off the machine and turn off at the wall, but leave plugged into the socket (it gets a chassis earth that way). Carefully remove the fan. Very briefly turn the power back on and try to boot up. If it boots up, then the fan may have stressing the mobo pcb too much and causing a short to the case or other intermitant fault. If it does run, turn it off again quick, re-fit the fan and try again - this will confirm if the fan is stressing etc. If it is then your mate needs a different fan or better case etc.
If no go without the fan, take a deep breath and carefully remove the cpu. Check no damaged pins (don’t touch any with your bare fingers). Re-seat making sure it’s the correct orientation and fits correctly. Then try briefly without the fan again. If it boots, shut it down and fit the fan and all should be hunky-dory.
If still no go, it is possible the cpu or mobo could have been damaged during the fitting of the new fan. At which stage, unless you want to go much deeper, it’s maybe time for a new mobo 
/edit…looks like you fixed it while I was typing! Good job!
yep defo the mobo lucky he got a spare sitting around so he wants me to fit it to a new case he’s getting and new HDD asked if he could watch i said no I’LL WATCH while he fits it all …lol that way if it goes all wrong it’s his fault …lol
so hope you’ll all be on standby on monday for when i start shouting for help:D
good game good game 
lol i win the brucie bonus