My pc doesn't start after cpu cooler change

[Iraklis]

Hello today i try to change my cpus cooler(yes i apply thermal paste) i did it and then i try to open my pc but then my screen was black and keyboard-mouse had no power but everything else inside the pc was working properly(cpu fan other fans)also i noticed that when i start my pc o don't hear thedistinctive beep sound that i used to hear

 

[DRagor]

Double check cable connections. My suspect is 4-pin (or 8-pin, mobo depending) ATX cable next to CPU not connected properly.

 

[PcRigs]

If keyboard mouse had no power it mostly is because the BIOS post (power on self test) check is failing. Meaning that its not starting the computer because a major component is missing (its not detecting the processor fan?) So you have to check if it has been installed correctly. The distinctive sound stands for several reasons depending on motherboard, for example my motherboard beeps if it does not detect a display.

 

[Iraklis]

Hello and thanks,i double and triple check everything but still nothing,i can't understand what is wrong also the sound that i speak about i think that is the sound of the processor,the cpus fan working properly but i don know if my motherboard recognizes it(i try both the old and the new)

 

[DRagor]

Are you sure you have connected cpu fan to the RIGHT header (the one labeled CPU_FAN)?

 

[Iraklis]

Yes and the odd thing is that the first time i assembly my pc i put it on the cha fan instead of cpu(i know rookie mistake,but i'm rookie after all)and it use to work just fine

 

[DRagor]

Yes and the odd thing is that the first time i assembly my pc i put it on the cha fan instead of cpu(i know rookie mistake,but i'm rookie after all)and it use to work just fine

The fan would work fine connected to any fan header, it's just regular fan after all. BUT the PC would think that there's no CPU fan and wouldn't start (well, at least it shouldn't, but some mobos might actually don't mind).
Did you uninstalled any components during cooler change? RAM perhaps? Is your motherboard equipped with beeper?

 

[Iraklis]

Yes i took out the graphic card,it didn't had in the package but i put the one that i had to my previous motherboard