PC won't turn on, PSU fan is jerking when connected to mobo

Question

My problem started from my initial PSU dying, I think, from the frequent power interruption in my place. I didn't use UPS before because the power interruptions isn't that frequent, but a few weeks ago we got multiple simultaneous ones and I think that killed my PSU. My PC won't turn on even if I only connect the 24pin, a HDD, a stick of RAM and the CPU. I tried to turn it on multiple times. I even got a Windows screen that I've seen for the first time, saying that it needs to repair my start up, something like that. Sometimes it would reach the login then die. After a while, it didn't turn on at all. Even removing the CMOS battery doesn't bring me to the BIOS. After reading about power interruption's chance to kill a PSU, I concluded that it might be actually dead now. So I bought a larger PSU than before because I was also planning on upgrading. My previous one is a 550w and the new one is a 850w(I got lucky and found it on my favourite online shop, it was quite cheap so I bought it as soon as I can, and it's modular so it's a win-win for me). The new one is an MSI A850GF.

When the new PSU arrived, I tried it out as soon as I can. I hooked it up to everything, but my pc still won't turn on, and the scary thing is that the PSU fan is jerking, and my keyboard's indicator lights (the ones for caps lock, num lock. I don't know what they're actually called) are flashing in sync with the PSU fan jerks. The PSU was brand new, so I looked how to test a PSU, and found the paper clip test. I don't have any paper clip so I used a zip tie. The case fan spun and the PSU fans spun just like how it should be. I tested it again today and noticed that the CPU cooler is spinning, so I think the board got power in it. I tried to connect the power switch pins using a screwdriver (forgot the actual term for it) but it still doesn't turn on.

I don't really know anymore how to fix this, or if it's even fixable. My HDD might have died as well after all that testing I did, and I don't really want to spend more money on that PC if possible because I want to upgrade anyway. If guys got any ideas what happened, please let me know.

Update: I did a last test and this time I touched the HDD. I don't know if that's how it should be, but I don't think shouldn't, but the HDD is grounded. I felt it, and it's quite strong. So I guess that it's already fried by that ground.

Answer 1

The symptoms you described typically occur if the power supply is overloaded. The supply starts up, then goes into over-current shutdown. With it shut down, it is no longer overloaded, tries to start up again, gets overloaded again and shuts down, etc.

Unfortunately, it is possible that when a power supply dies, it sends a surge to something connected to it, frying that too and causing it to develop a short circuit.

You should try connecting only your motherboard, with all cards, memory, etc. removed, just the mobo and CPU. Hopefully, it will start up and beep due to lack of memory and video card. If not, either your mobo is fried or the PSU is bad.

If that works, power off and try re-adding the memory, then the video card, then other cards then other things (hard drives, etc.) until you get the symptom again. This will tell you where the problem is. If you have a beefy video card, it may be that the PSU cannot drive it. Otherwise, whatever causes the symptom is probably shorted out.