Question Pc shows no life after cpu switch

[Mr72]

hi, i was using an Amd A6 6400K and switched to an Athlon 760k, after switching, i connected everything back on and hit the power button, it suddenly started and shut down right after, then i tried to power on again but got no video (yes, the bios was set to use PCI graphics), so i decided to put back the A6 cpu and the same thing happened.
i'd think it is a PSU problem. But it was running before
What could it be? How do i do a Post?
I had switched the cpu a few years back but was for the same model and everything went well

Also im getting no beeps from any audio exit

 

[DSzymborski]

What are the full specs?

 

[Mr72]

gigabyte ga-f2a55m-s1
amd a6 6400k (old)/ athlon x4 760k (new)
8gb ddr3 1600mhz single channel
radeon hd6570 2gb gddr5
7200 rpm seagate HDD
WD green sata SSD
400w psu

 

[DSzymborski]

And the exact PSU?

 

[Mr72]

It is a bluecase BLU400R-80E psu(they say it is 80+ but i doubt it is genuine), i didnt had any issues with it in the past few years though, i would understand if it didnt have enough power to the athlon, i started to save to get a proper 80 plus psu in case i needed one after ordering this processor, i will only be able to afford one at february because i refuse to use credit card, but my problem is that now it the computer isnt working, i would have no problem having to wait a month to use the Athlon, but im unable to use the old harware as well
Someone told me to get a beeper, but the hardware stores are closed due to holidays, and if i oder online, would still take a week
I can wait, but if i could have any idea now, it would help

 

[Third-Eye]

hi, i was using an Amd A6 6400K and switched to an Athlon 760k, after switching, i connected everything back on and hit the power button, it suddenly started and shut down right after, then i tried to power on again but got no video (yes, the bios was set to use PCI graphics), so i decided to put back the A6 cpu and the same thing happened.
i'd think it is a PSU problem. But it was running before
What could it be? How do i do a Post?
I had switched the cpu a few years back but was for the same model and everything went well

Also im getting no beeps from any audio exit

Did you reset the bios before swapping CPUs or at any point during the process? You should always reset the bios before changing CPUs.

 

[Mr72]

Did you reset the bios before swapping CPUs or at any point during the process? You should always reset the bios before changing CPUs.

I did set it to default
Btw, i managed to get a beeper, if i put a ram on Slot1 it beeps pointing to faulty ram, but if i put the stick on slot 2, it doesnt beep at all, and if i remove the stick, it beeps continuously

 

[Mr72]

Update: another guy told me to short the bios using the jumper, it booted now, i will save for a quality psu for the future, sorry for the inconvenience guys