installed new PSU in my computer it won't turn on :(

[RayRay]

I see.
This is definitely starting to sound like a motherboard problem.
But as said before, you should follow the instructions in my initial post in order to rule out other factors:
https://www.eevblog.com/forum/chat/installed-new-psu-in-my-computer-it-won't-turn-on-(/msg1177596/#msg1177596
I gave you some very simple instructions on how to test the PSU, power button,and a possible short between the motherboard to the case.

Edit: You could also test the power cord (while completely disconnected) for continuity across all 3 points from end to end, and check that neither is reaching each other (shorting). I highly doubt the power cord is the issue, but worth a check.

[sony mavica]

i now can get the new psu to turn on fine if i unplug the 8 pin connector by the cpu fan

[RayRay]

That 8PIN plug provides power to the CPU.
And CPUs very rarely go bad, so it's clearly a motherboard issue.

[sony mavica]

That 8PIN plug provides power to the CPU.
And CPUs very rarely go bad, so it's clearly a motherboard issue.

i ust noticed on of the clips on the cpu fan that holds it down is broken

[RayRay]

Could you take some pics?
Also, is there something you forgot to mention? Did you in any way fiddled with the CPU fan before any of this started?

[sony mavica]

Could you take some pics?
Also, is there something you forgot to mention? Did you in any way fiddled with the CPU fan before any of this started?

i had problems last year around september once i cleaned my computer of dust ect and cleaned the cpu fan ect and put new paste on it the pc had no problems till around 2 or 3 weeks ago

[RayRay]

That doesn't fully explain it though!
Clips definitely don't break on their own.
You didn't do any other "physical" activities in there shortly before the problem started?

[sony mavica]

That doesn't fully explain it though!
Clips definitely don't break on their own.
You didn't do any other "physical" activities in there shortly before the problem started?

nope

[RayRay]

Okay, maybe I got a bit caught up on that one. 
Anyhow, I'd say it probably got broken a while back (while you were servicing the cpu fan).
But this is likely a moot point (if it was sitting relatively well and worked fine for several months then it couldn't have been too much of an issue)
And I'm starting to get a very clear picture of what happened here!
Seems that at some point, the CPU fan failed, you couldn't have known, and the heat caused damage (to the cpu, motherboard or both).
I'd say you should be looking at getting a combo of a new motherboard/cpu/ram.
I could help you pick em if you want to.
Also, just a word of advice, if your case doesn't have a side window, then better get one that does (and put it next to the monitor where you can actually see thru it!) this could give you a heads up next time.

[sony mavica]

so the cpu could be bad would a will FCLGA1155 socket i3 cpu i know works fine  work on LGA1155 cpu socket?

do you think switching the cpu would help?

[sony mavica]

so the cpu could be bad would a will FCLGA1155 socket i3 cpu i know works fine  work on LGA1155 cpu socket?

do you think switching the cpu would help?

Why an LGC1155 i3 won't work on an LGA1155 mobo if both are functioning?

should i swap i7 cpu for the i3 i know that works and to see if the i7 cpu is dead?

also i plugged in my old  psu with the 24pin connector and the 8 pin connector and computer powers on for like 1/2 seconds and then powers off again and if i try turning it on again it just keeps switching off in the half a second

[sony mavica]

should i swap i7 cpu for the i3 i know that works and to see if the i7 cpu is dead?

also i plugged in my old  psu with the 24pin connector and the 8 pin connector and computer powers on for like 1/2 seconds and then powers off again and if i try turning it on again it just keeps switching off in the half a second

1. Yes. It is extremely rare that a faulty mobo will take down the CPU, so there is no significant risk involved.
2. That means something on your mobo is wrong. Be the CPU or bridge. RAM fault usually doesn't cause immediate shutdown.

My $0.02: when removing and reinstalling ATX connectors, external force caused some solder joint to snap off.

i don't think any of the solder joints snapped off as i can still get it to power on with the 8pin connector plugged in with the old psu just not the new one

this problem is so annoying im about ready to chuck this pc out the window

[sony mavica]

Man i am so dumb it turned out i never noticed another cable on the new psu and that i had plugged in the wrong pin connector and now pc boots up fine thanks for all the help guys

[DimitriP]

If it's not a bad connection of the  motherboard power connector

It always sucks when the wrong connections are good !