cpu and psu fan start for second and stop after gpu upgrade....no display

[sgtech]

my specs
ecs h81h3 m-4 1.0A-MOBO
intel g3240-processor
2 gb ram
psu-corsair vs550

i installed corsair vs550 and everything was working fine...then i installed the amd radeon r7 250x and the good news stopped there....the cpu and psu fan would spin for a second and stop...also i am using a 10 ampere plug for corsair psu....since the one it came with did not fit the socket.everthing was working fine but after installing the gpu these problem started.

then i took the gpu out and started to boot from onboard integrated graphics but the same problem....cpu psu fan start and then stop after a sec....

 

[alexoiu]

Try RMA-ing the power supply, or testing different one.

 

[sgtech]

but i tested the psu and it works fine....

 

[cirilo_escomp]

but i tested the psu and it works fine....

There is a lot of sensible information on a similar subject at
http://www.tomshardware.co.uk/forum/304402-28-starts-stop-start

My particular case was a little bit different with the same symptoms...

Power switches are always OFF nowadays. When you press them,
they send an ON pulse and the computer starts. Press them again
a little more for a longer ON pulse and the computer stops.

I tried several motherboards and PSUs that started and stopped until I
realized that a loose wire short-circuited the Power switch so it was
always ON (start... and stop).

So check also Power (and may be Reset) switches and connectors
to the motherboard.