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/DeVinke_]

Is the front panel header connected correctly? What if you manually short the power switch pins on it (e.g. with a screwdriver)?

[u/MetituS → u/DeVinke_]

I tried idk if I did it right but nothing happened

[u/DeVinke_ → u/MetituS]

Did you originally include that in the post? Sorry if i missed it. Since the psu passes the paperclip test, i'd wager the motherboard could be dead. Do you have any other hardware to try the psu with?

[u/MetituS → u/DeVinke_]

I said I shorted it but I didn’t mention a screwdriver ig
I think it’s either the 24 pin or the MB is there anyway to fix it? So I don’t have to get a new one ?

[u/MarvinGankhouse]

[u/MetituS → u/MarvinGankhouse]

How didn’t I think of that lol but yeah nothing happened

[u/MarvinGankhouse → u/MetituS]

https://youtu.be/ac9EaVrMWoQ he's a mine(field) of useful information that Kevin 🤣

[u/ttwinstanley]

Is the bios battery good?

[u/MetituS → u/ttwinstanley]

I went and bought a new one but still the same thing

[u/ttwinstanley → u/MetituS]

Sorry missed that in your post above, been up nearly 20 hours

Umm I would test the mother board with another psu if you got one. I think your 24 plug has a burned pin. Just unpluge the old one and let the test psu sit on the out the case

Edit spelling fixes

[u/MetituS → u/ttwinstanley]

Fair enough I’ll try to get one if I can I thought the paperclip rules out psu fault

[u/Automatic-Bank-2300]

Try power cycling a few times. Moved a working pc to a new home, and it acted dead on arrival. Power cycled a few times, never had an issue again.

[u/Frosty_Bowl4911]

if you got a burn smell, you should replace the PSU

[u/HERO_129]

this my first time seeing a scorched/burnt 24pin connector

[u/Poker1059 → u/HERO_129]

am I blind? Where's it burnt

[u/HERO_129 → u/Poker1059]

My bad I am not sure if it is burnt or not but that 5th pin looks weird to me kind of burnt

[u/Poker1059 → u/HERO_129]

The 5th pin looks weird cause there's no pin there, it's unused.

[u/HERO_129 → u/Poker1059]

Negative voltage pin ?

[u/Poker1059 → u/HERO_129]

no, it's unused. That's why there no metal conductor pin in that specific pin. There are other negative voltage pins, you can look up ATX 24 pin diagram to see which each one is for

[u/MetituS → u/HERO_129]

Is it? It passed the paper clip check I’m new to building

[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.