A strange problem with my new PC

Yesterday it wouldn't boot. No sound from the PSU, fan is not running. Then suddenly after a couple of hours it changed it's mind and decides to boot after all. And then it does, it worked flawlessly. Today - same problem, until it decided to boot again.

I've changed the power cable and connected it to another outlet. I have removed and reinserted the cables going to the motherboard, both on the PSU and the MB. No change. There's an on-off button on the MB itself but that doesn't improve things either. However, the lights on the MB are on all the time, so there's at least some power. Nothing in the event log (which probably isn't that surprising).

Naturally I wonder who, or rather what to blame. PSU? MB? Other things?

The PSU is a Corsair RM850. Maybe it's too weak - currently I have two 980's in the machine, 32 GB RAM and 3-4 hard disks. But if that's the case, why does it sometimes power up? And why does it work just fine, without crashes when it does?

Any ideas?

More technical data:
MB is ASUS Maximus Hero, with an Intel 4790k CPU. I haven't overclocked anything.
Win 8.1 64.
Case is black with a few nice read LED's.
And it's got wheels.
…

pibbur who now is more confused than he normally is.

I'd have thought that a quality 850w PSU should be enough, though it could be cutting it fine under full load. The GPUs wouldn't be drawing too much power until they get busy, though.

My first suspicion would be a defective PSU, since it should spin up even if there's other problems in the system. These problems can be almost impossible to identify with certainty unless you have some spare components to test with

Although I don't expect it to be the problem, I'd start by removing one GPU, and one DIMM, and then swapping them over, to eliminate at least some possibilities.

pibbur who said:

And it's got wheels.

Click to expand...

HA! Looks we've found the culprit. You need to change these wheels immediately for stands!

OK, on a more serious note, I do not necessarily believe that the PSU is too weak but if the PSU does not even start up (right? you push the power button and absolutely nothing happens, right?), it sounds like there may be an issue with the PSU surge protection. Maybe it "thinks" it needs to protect itself from overvoltage. Or the mainboard does. The board has a setting for surge protection in the UEFI BIOS which you could try to disable for a few starts to see if that is the culprit. Could be risky of course...
It could also be a bad mainboard battery. You could try changing that one or take it out for a few seconds and put it back in. You might have to readjust BIOS settings after that procedure.
Or there is something other electrical not working quite right. For example, some fans refuse to power up in conjunction with certain PSUs and can cause all sorts of issues. Thinking about it.... that should be your priority.

So I'd recommend the following:

- First unplug all fans except for the CPU fan obviously . See if that changes anything.
- Next try the surge protection options in the BIOS.
- Thirdly try swapping out the battery.
- Finally, if all of the above fails, carefully examine your system for potential electrical faults. Are all the standoffs installed correctly so the case and MB are separated from each other? Are all of the RAMs inserted correctly and firmly in place? Same for any PCIe cards? Maybe try removing the SLI bridge for a few startup attempts, too. Ideally, remove and put back in place all RAMs and add-on cards to make sure they are firmly in place as they should be.

Final-finally, you do have the latest UEFI BIOS installed, right? If not, then that might be worth a shot as well, of course.

Good luck!

The two possibilities that pop in my head are either psu or motherboard. Power supplies go out much more than motherboards so test that first. See if you can borrow one from another system and see if it acts normally. . It's a new system so you shouldn't have any swollen capacitors but check the motherboard just to be safe.

Also do as Ripper suggested and get your system as lean as possible, with 1 disk, 1 GPU, etc. I would also say PSU since mainboards are not likely to cause these kind of boot issues (normally). Good luck with the testing.

I would flash the bios first as that's easy.

Then test the PSU, then I'd tear it down totally and rebuild it. Booting it up with the bare minimum of components. Reseat the cpu with new thermal paste and reseat mem. Use intel graphics for first boot. if it works add other components 1 at a time to see if it fails.

If the power supply fan is not running, I'd bet that's most certainly your problem. Even though Corsair is a quality manufacturer, I've had bad power supplies before so I'd focus on that first.

I had a similar problem many years ago when one of my main board's electricity capacitors was damaged - but that board was several years old, then. And I found it out only after I had replaced the board - had to, because in the end it didn't want to start anymore at all.

And if you using an optical drive, do a chkdsk on it. I had a similar starting issue on a computer at work and it was a bad block that just happened to have a Windows system file in it.

Like Toff said, most likely PSU problem. Evidence is overwhelming. Other possibilities are MB or even power switch issues, but unlikely.

I had problems with my PSU recently and would suggest two easy tests to check if the culprit is PSU or the MB:
1- make sure that the two connectors delivering power to MB are sitting firmly in their MB's sockets. Apply pressure to make sure that they are.
if it will not solve your problem try
2- from system panel connector remove wires from the two power switch pins and connect the two pins with screwdriver or something similar (it is safe and you will not damage your PSU) if PSU will come to life means that you have MB problem.

Unlpug then plug back *everything* inside the rig. Except CPU ofc, just check if the CPU fan is firmly attached on the motherboard.

What you're describing and zarathustra already mentioned is something I've seen when PSU cord plugged into the motherboard was a bit lose so PC sometimes wouldn't start or would turn off while working without an apparent reason.
Oh yeah, imagine playing no saving anywhere crapware conoleports on such PC till you find out that all you had to do is cable checking. Horrors!

One quick question, as I'm going to try another psu. Turns out that my old machine has an 800 watter. If the plugs (headers?) fits the thingies (headers?) on the motherboard, it should be safe to connect it?

Pibbur who mostly thinks about cda when it comes to headers.

pibbur who said:

One quick question, as I'm going to try another psu. Turns out that my old machine has an 800 watter. If the plugs (headers?) fits those on the motherboard, it should be safe to connect it?

Pibbur who mostly thinks about cda when it comes to headers.

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I believe so, yes.

pibbur who said:

One quick question, as I'm going to try another psu. Turns out that my old machine has an 800 watter. If the plugs (headers?) fits the thingies (headers?) on the motherboard, it should be safe to connect it?

Pibbur who mostly thinks about cda when it comes to headers.

Click to expand...

Should be fine.

Switching PSU didn't help, so back to the old one. But I think you'll all be happy to know that it seems I've got it to work now, the last couple of days it has started flawlessly whenever I wanted it to.

Here's what I did:

Nothing.

Except threatening to return it to the people that originally built it for me (before I replaced the MB and such, resulting in a few unfortunate consequences), so they could deal with it. Harshly. It seems like it got scared.

I won't be surprised if that's the case. I've always claimed that the gnomes that created havoc farms back then, unless properly and generously, bribed with porridge (at least that what we did in Norway.), they have moved into our networks, servers, switches and in general components, doing their nasties there. No one can deny that it at least seems like they did. Don't know how to bribe them, unfortunately.

Artificial intelligence? I think we'll say its all about gnome intelligence.

Pibbur who refuses to embed his MB and PSU in porridge. Unless watchers he trusts recommends that very procedure (which of course immediately will make him distrust them).

pibbur who said:

Switching PSU didn't help, so back to the old one. But I think you'll all be happy to know that it seems I've got it to work now, the last couple of days it has started flawlessly whenever I wanted it to.

Here's what I did:

Nothing.

Except threatening to return it to the people that originally built it for me (before I replaced the MB and such, resulting in a few unfortunate consequences), so they could deal with it. Harshly. It seems like it got scared.

I won't be surprised if that's the case. I've always claimed that the gnomes that created havoc farms back then, unless properly and generously, bribed with porridge (at least that what we did in Norway.), they have moved into our networks, servers, switches and in general components, doing their nasties there. No one can deny that it at least seems like they did. Don't know how to bribe them, unfortunately.

Artificial intelligence? I think we'll say its all about gnome intelligence.

Pibbur who refuses to embed his MB and PSU in porridge. Unless watchers he trusts recommends that very procedure (which of course immediately will make him distrust them).

Click to expand...

Most likely the MB then. And no never porridge.
Chocolate milk is the better choice.

Just leave the computer on. Never turning it off will fix the start problem for sure.

My previous pc would turn itself off after 1 second or so after pushing the power button. This happened 30% of the time, other times it just booted fine with no further problems. It probably was the PSU/cable sometimes shorting against the case I think. So yes just leave it on

Speaking of rare problems. I got random freezes while gaming. sometimes after 5min, sometimes I could play for hours. I tried EVERYTHING. Turned out (after more than a year) it was a bloody tiny hair in the agp slot. I learned my lesson.

Latest news. I had to replace the MB, this time with a Maximus vii Formula, which seems to be more robust, and had a couple of other nice features.

Now the boot problems are gone. However initially I had problem getting it to recognize inserted memory. On the net I saw several people mention this could be caused by bent pins in the CPU socket, so I opened it, and lo: one of the pins was in deed bent. Maybe I was a bit careless when inserting the CPU (hasn't happened before), or maybe it was so already when I got the MB, but I didn't examine the socket before installation. Or maybe I'm cursed (dropping my iPhone in the toilet, a couple of other unfortunate events). Anyhow, armed with a needle and some patience I managed to fix that, so now everything is on the green.

I admit I was a bit nervous before the procedure, but then I remembered my days as a general practitioner. Quite often I got patients who had been a bit unlucky and got foreign bodies like pieces of iron/other small things stuck into their corneas. So I had to, once again armed with a needle, scrape away a bit of said part of the eye, in order to remove said foreign body. The cornea is about 1 mm thick (or thin if you want), but I never punctured it.

pibbur who claims that procedure was one of the very few things he liked about working as a doctor. But it wasn't nearly enough to make him stay in that profession.