Desktop PC won't start (prime suspects are PSU and motherboard)

MikkelVejs

Reputable
Sep 20, 2014
7
0
4,510
0
So I've recently run into problems with my pc. It started out with the pc just not showing me the ASUS logo screen, then I'd restart it, and it would boot up windows like nothing had happened.
Today I haven't been able to get into windows or see the logo screen at all. I've tried unplugging all the cables connected to the power supply and put them back in, but that din't work. I noticed on the PSU, that the 24 pin connector doesn't go all the way in and doesn't make that click the other cables do when i insert it into the PSU. I've also tried taking out the cmos battery and that didn't work either.
Are there any other things I can try to sort this out? And do you think I'm right in thinking it's the PSU or motherboard?

Specs are:
ASUS Z97 motherboard (don't remember the name)
Intel i7 4790k
8gb RAM
GTX 780
Corsair RM650 PSU
(old machine, I know :D)
 

Darkbreeze

Titan
Moderator
Old, but still VERY relevant. Not THAT old, really. Well, except maybe the graphics card and if the power supply was already in use before that system was built, maybe the power supply too.

Disconnect the PSU connectors to the motherboard and check to see that none of the pins on the motherboard socket are bent.

Check the ends of the cables to make sure none of the socket connections inside the socket are bent or damaged.

If all else fails, test the PSU with a multimeter.

https://www.youtube.com/watch?v=ac7YMUcMjbw

Visually inspect the motherboard to see if there are any leaking or bulging capacitors, or other signs such as burnt spots.

Last case scenario, bench the motherboard.




 

MikkelVejs

Reputable
Sep 20, 2014
7
0
4,510
0


None of the pins on the motherboard socket were bent, and neither were the socket connections on the inside of cables. And no sign of motherboard damage either.
I don't have a whole lot of equipment lying around for troubleshooting, so I guess I'm just gonna have to take it to a shop downtown and see if they can find out what's wrong.
Thanks a lot for your help though!
 

Darkbreeze

Titan
Moderator
You can pick up a multimeter at Harbor freight for six bucks, or like 14 bucks at any Walmart. That's a lot cheaper than the cost to have a shop look at it.

And if your PSU is more than 4 years old, there's always a good chance that replacing it with a quality unit might be the fix right off the bat. I'd rather put the money into replacing a unit that you already know has some miles on it, if it does, than give it to a shop to tell you what you could determine for yourself.
 

MikkelVejs

Reputable
Sep 20, 2014
7
0
4,510
0


Well, we don't have Harbor freight or Walmart in Denmark, but I'll see if I can find a multimeter somewhere. But if it really is the power supply, wouldn't the pc shut down or freeze when it's running windows? Because once I could get the pc running, I wouldn't encounter any issues until I tried to start the pc the next day.
 

Darkbreeze

Titan
Moderator
Yeah, that's for sure. Sorry man, I didn't realize you were IN Denmark. For future reference, this is a good example of why it's always a good idea to offer where you are because hardware availability, and other considerations, are able to be accurately targeted for your specifics, so as to not waste time giving you suggestions that are either not feasible or not available to you in whatever region your in.

So if you can find somebody with either a digital or analog volt meter, even a cheap one, that should be sufficient for basic testing of the power supply.

My biggest concern right now though is that you said the 24 pin connector is not fully seating and I'm about 99.999% sure that is likely to be your problem and we need to figure out WHY it's not seating. These things don't just "not seat" unless something is wrong. Either the physical plastic framework of the 24 pin ATX connector is warped, from heat, or the plastic is othewise malformed such as a gash that has created a part of the connector that doesn't want to fit inside the socket it needs to plug into, or there is something bent in terms of how the pins in the ATX connector on the motherboard or the female pins inside the plug are sitting.

Or, there is a foreign object sitting down inside the 24 pin socket on the motherboard that is not allowing it to seat.

There are really no other possible reasons for why it would not seat, and without it fully seated, problems. I've seen plenty of systems with the ATX connector that looked like it was fully seated, but wasn't actually in enough for that final little "snick" where the locks engage, that either would not run or ran but had a bunch of ghost problems.

With poor electronic connections, sometimes once you get them to start the flow of electrons WANTS to continue flowing, so you won't see any major issues during operation but getting them to start over a tenuous connection in the beginning can be a different story. Check the things I listed above and then if you don't find anything, try lightly pressing down on that connector into the socket while you attempt to power on the system. You may need an assistant in order to do that because, well, we only have two hands.

I would also take a look at everything outlined here. There is nothing not worth looking at, even if you THINK it's ok:

**Click here for help troubleshooting hardware and No-POST issues

I really feel like your 24 pin connector is probably the source of the problem, if it's actually NOT seating all the way, but of course it COULD be something else so don't ignore any other possibilities if the connector troubleshooting doesn't bear fruit.
 

MikkelVejs

Reputable
Sep 20, 2014
7
0
4,510
0


Alright, sorry for not specifying region, still kinda new to this forum thing :D. But I'll definitely take a look at the things you suggested! Thanks a lot, again.
 

MikkelVejs

Reputable
Sep 20, 2014
7
0
4,510
0


Alright, so turns out it can start if I push on the 24-pin connector on the PSU side! Still no apparent way to tell if it's the cable or the PSU itself, though. Guess I'm gonna try buying a new cable first, since it's the cheapest option.
 

Darkbreeze

Titan
Moderator
I wouldn't do that unless you can determine for certain that it is the cable. There has to be a reason why the cable needs to be pushed further into the socket, and unless you can visually see a reason on the end of the ATX cable, then it's likely something inside the PSU. Check for bent pins in the PSU socket, or foreign objects in there. Check the plug on the cable for deformities, check everything. There has to be a reason. Cables don't just not plug in correctly automagically. There has to be a reason why they don't "snick" into place, and if they do, and there is still a problem, then the problem is with whatever they are plugging into, not them themselves unless you can actually SEE something visually wrong.

Honestly, I'd like to say you need to just replace the unit for safety reasons, but I understand the desire to save some bucks as well.

And if you DO replace the cable, it can't just be any old ATX cable. It MUST be for the RM series units specifically because the pinouts between power supply models that are not absolutely identified as having the same pinout on the modular cables, such as the G2, G3, P2 and T2 EVGA units all being the same, are usually different in pinout even if the physical configuration of the socket is the same.
 

ASK THE COMMUNITY