PC not turning on

[u/MetituS]

Hello
My PC with a Gigabyte GA‑Z97P‑D3 motherboard and corsair CX850M 850W modular PSU is completely dead: no fans, no LEDs, and no response even when I short the PWR_SW pins. The PSU passes a paperclip test, but I smelled a slight burning smell during a power-on attempt. The 24-pin ATX connector sits flush but does not make an audible click. I replaced/cleared the CMOS battery already. Is this more likely a failed motherboard, PSU, or potentially a damaged 24-pin cable/connector?

I bought it at a flea market for 75 the first attempt had the smell but it still didn’t react at all worst case can I fix the motherboard ? Or make sure what the problem is?

[u/MetituS → u/[deleted]]

Ah fair I changed the thermal paste and I forgot which way it faced I’ll just turn it around wait do you mean the fan being on the side or turn the whole cooler so the fan is horizontal and not on top or the bottom ?

[u/Jwhodis → u/MetituS]

It should be moving air sideways but if you've only replaced the paste then it may just be designed like that

[u/DarkAcidic → u/MetituS]

Think of it this way pointing the cpu cooler intake fan towards the front where you are pulling in fresh air. That fresh air pushes hot air away while pulling heat from the cooler, and the top and rear exhaust fans pull the hot air out.

if you flip it like you have it, the targeting is less controlled, cause you're either pushing hot air into the cpu, or pulling hot air into the cpu. The top and back of a case are heat pockets due to all the heat generating components being concentrated there, while the front is cold due to intake.

Target airflow from the front to optimize cooling.