Question PC does not POST since GPU upgrade

[Mr_Lou]

After the upgrade the PC and the fans span for around 5 seconds then stopped and started again this continued until I cleared the CMOS then the fans span for 25 seconds and didnt repeat but stayed on still no post, I checked the RAM and removed the GPU to see if it was malfunctioning, but the PC won't post and I can't think of what to do

System specs
i3 4160
450w psu
h81-i
1660ti (was a 750ti when it worked)
1tb Hard-drive
8GB ddr3

 

[Grobe]

Does it work if you put back the old GPU ?

Was the computer stable before you upgraded the GPU ?

What model and how old is your PSU ?

You sure you haven't forgot to connect the power to the PSU ?

 

[Mr_Lou]

yep it has enough power the gpu is 500w and its about 3 years old, its a corsair builder series. It ran stable with the old gpu dont know if it works with the old gpu. I know it dosnt work on the integrated gpu though

 

[Grobe]

Power to GPU ok?