PC won't post

[IronWarrior]

So I finally put my PC back into it's case and it wouldn't turn on, found out the power on switch was broken, so replaced that and that fixed the power issue.

So turn it on with everything connected, there is no POST. Screens don't detect anything from the PC, the fans are spinning, HDD's are working, GPU is working, there are no speaker beeps from the motherboard. PC doesn't crash as well, just keeps running. The Keyboard and Mouse and other USB devices don't power on as well.

One of the things I read is that the motherboard could be shorting out? This is the first time I reseated it.

I'm going to start breaking it down now and test it with limited parts.

[Disturbedguy]

I had an issue a while ago, due to not RTFM.

Put RAM in wrong slots, would not boot, moved RAM, booted.

[IronWarrior]

Well, it's working now. Just using the core parts, one HDD, GPU and 4 RAM and it posts and loads Windows fine.

So it must been shorting out... So how do you avoid that?

[IronWarrior]

Can metal paint short out an motherboard?

Every time I install the MB into the case even with the screws totally lose, it won't POST. Take it out and it will POST and work fine.

Back to this till I can fix that problem!

[kalniel]

Could be the IOshield.

Or could be a standoff - to eliminate the latter take it in turns to remove a standoff position.

[IronWarrior]

Could be the IOshield.

Or could be a standoff - to eliminate the latter take it in turns to remove a standoff position.

Ah, if it's the IOshield, what can I do about that? Try reseating it?

Standoff's, the screws that go into the tray for the motherboard to sit on? So... change them around?

[Disturbedguy]

Ah, if it's the IOshield, what can I do about that? Try reseating it?

Standoff's, the screws that go into the tray for the motherboard to sit on? So... change them around?

Yup stand offs are the brass (?) looking things that screw into the motherboard tray and the motherboard sits on.

[kalniel]

Ah, if it's the IOshield, what can I do about that? Try reseating it?

Check it's not bent first of all. Check that the holes for the components are square on and there aren't any tabs contacting internal pins of any ports. Check that's pressed through fully etc.

Standoff's, the screws that go into the tray for the motherboard to sit on? So... change them around?

Those are the screws yes. Just remove one position a time (the motherboard should still balance OK on the remainder) to see if you can identify a single one what's causing the problem - it won't be the standoff itself, but once you've identified the position you can check the motherboard for any faults around that screw hole or contacting components (it *is* meant to contact earth).

Another possible:
Does your CPU cooler use a backplate? Is it anywhere near contacting the case or a standoff? Shouldn't be an issue, but might be worth putting some foam under it to help make sure.

[Demonwar]

Check for damage to any cable that touches the case/mobo. Check your repair job of the power switch is secure and not being pulled tight when you pull the mobo out and they going back in is resting on something metal.

[nightcypher]

It'd also be worth double checking that none of the PSU cables or anything else are showing any exposed wiring. It may not necessarily be the motherboard that is shorting directly. It probably is by the sounds of it, but it wouldn't hurt to check the above.