POST issue

FL630 · 25 Jan 2018 at 15:26

Here's a complex one to work out. The most annoying thing is it's not replicable in any way.

Setup is Asus ROG Strix Z370-F with i5 8600k, 16GB Corsair Vengance LED, Strix GTX980. All under a custom water loop.

9 times out of 10, I hit the power button and it boots within seconds. 1/10 it does not, it will not even POST.

Sometimes it's just a black screen, sometimes I see the ASUS logo, sometimes I even get the windows circley balls, which freeze and nothing happens. I've left it for half an hour, nothing happens.

POST LED's can vary between fixing on VGA or even showing a clean POST. Sometimes from this point, through a variety of resetting, BIOS resetting and patience, I can get it going. Sometimes this takes 10 minutes, sometimes hours.

I've tested RAM, one stick, two sticks, all the different slots. MEMTEST has been run and come back clear.
BIOS re-flashed to latest version
GPU drivers cleared, then reinstalled from fresh
Windows 10 reinstalled.
All overclocks removed from GPU/CPU/RAM(XMP only)

This morning, no luck, will not start. So I remove the GPU, and it starts, great! I choose to re-start with some intel graphics drivers. After, will not start, will not POST. Touch the Motherboard jumpers, restarts via the BIOS.

The only thing I've not tested (and cannot test easily) is my PSU, as I do not have a spare and don't know anyone who does within a reasonable distance.

When it does run, its rock solid. GPU will run with a seriously good overclock without a single artefact for hours and hours at a time.

Does it sound like a motherboard issue? It's the only thing I can put it down to? It's under warranty so I can return it for a replacement, but I just cannot work out what could be causing this?

Thanks

Plec · 25 Jan 2018 at 16:00

Are you running the system from an extension lead?

If so try mainlining it to a socket and testing.

And have you tried disabling fast/turbo boot?

EDIT: is the GTX 980 new to the system too?

FL630 · 25 Jan 2018 at 16:10

Plec said:
Are you running the system from an extension lead?

If so try mainlining it to a socket and testing.

And have you tried disabling fast/turbo boot?

EDIT: is the GTX 980 new to the system too?

Yes it's on an extension lead, I've tried several and direct from the wall, no problems there it seems.

Fast boot has been turned off, I thought it was helping things but then the problem came back. As I say, it's so unpredictable and random it's almost impossible to replicate.

GTX980 is about 3 years old, never skipped a beat. Right now it's on stock speeds but it's a really solid card. Right now I've got it running using onboard graphics, GPU is unplugged.

Plec · 25 Jan 2018 at 16:58

FL630 said:
GTX980 is about 3 years old, never skipped a beat. Right now it's on stock speeds but it's a really solid card. Right now I've got it running using onboard graphics, GPU is unplugged.

Are you using the DP port and were you before the upgrade too?

FL630 · 25 Jan 2018 at 17:15

Plec said:
Are you using the DP port and were you before the upgrade too?

Thanks for the reply. Yes, I've tried all the Display Ports, HDMI, but not the DVI.

This is the confusing part, is it GPU or Motherboard? I just can't work it out :confused:

Plec · 25 Jan 2018 at 17:52

How old is the the PSU - was it part of your old build (brand/model)?

FL630 · 25 Jan 2018 at 19:56

Plec said:
How old is the the PSU - was it part of your old build (brand/model)?

EVGA Supernova 750 G2. 2 1/2 years old. Using Shakmods cables, been in use like this for 9 months.

Problems only started on new build

facboy · 26 Jan 2018 at 00:21

No leaking? Random shorting from leak could cause issues.

Try a different keyboard. A silly question, is your desk messy, and if so, is there stuff around the keyboard?

FL630 · 27 Jan 2018 at 20:45

The plot thickens.

Took the whole system out of the case and built on the motherboard box. Being a hardline cooled system this was an utter ball ache, even more so as I had to re-plumb it out of the case as I have no air cooling parts.

@facboy clean desk. Haven't got another keyboard to try.

What could cause the PC not to run in the case but almost perfect out with?

mistersprinkles · 28 Jan 2018 at 08:20

Use an extension lead certified for air conditioners. PC's pull a lot of power and it's a sustained load. Overheating electrical leads is a bad thing.
having said that pretty sure you're not supposed to plug a power strip/surge arrest into any kind of extension, period.

Skynet5 · 28 Jan 2018 at 09:18

FL630 said:
The plot thickens.

Took the whole system out of the case and built on the motherboard box. Being a hardline cooled system this was an utter ball ache, even more so as I had to re-plumb it out of the case as I have no air cooling parts.

@facboy clean desk. Haven't got another keyboard to try.

What could cause the PC not to run in the case but almost perfect out with?

Well if it runs find for the next few days, then I'd say something was getting shorted by the case?

EsaT · 28 Jan 2018 at 09:40

FL630 said:
The plot thickens.

Took the whole system out of the case and built on the motherboard box. Being a hardline cooled system this was an utter ball ache, even more so as I had to re-plumb it out of the case as I have no air cooling parts.

What could cause the PC not to run in the case but almost perfect out with?

As problem started after new build are motherboard standoffs in correct positions?
(with correct number)
How well graphics card is in its slot?
(not bending/hanging much)

Such intermittent problem could fit to little shaky contact affected even by room temperature.
Hardline piping could also bend something little.

EsaT · 28 Jan 2018 at 09:43

mistersprinkles said:
Use an extension lead certified for air conditioners. PC's pull a lot of power and it's a sustained load.

Standard home has many other and heck lot more power consuming things than PC.
For example vacuum cleaner is heck lot worser power hog.
So you should be using finger thick power cord for that...

mistersprinkles · 28 Jan 2018 at 21:48

EsaT said:
Standard home has many other and heck lot more power consuming things than PC.
For example vacuum cleaner is heck lot worser power hog.
So you should be using finger thick power cord for that...

Vaccuum runs for 15 minutes at a time. High end gaming PC running SLI can draw 700W sustained over a 6 hour gaming session.

You shouldn't run vaccuums on extension leads either. BTW most vaccuums I have ever used if they run non stop for over 20 mins the lead gets very warm.

FL630 · 1 Feb 2018 at 12:24

Okay so after the success of the system booting and running outside the case, I rebuilt it back into the Corsiar 570X, topped the water up and hit the power button....

Blank screen, no display output. Tried the other two DP's, nothing, HDMI, nothing. Unplugged the GPU, HDMI into the motherboard display out, no boot.

I've checked the motherboard standoffs, all the screws are in, nothing there that could be shorting the motherboard. All cables attached securely.

Interestingly, I note as I type this, the motherboard POST LED's no long illuminate on start up.

Going to try drain it again, pull it all out, rebuild again and see if it works out of the case.

I hate computers.....

Plec · 1 Feb 2018 at 12:43

Before you drain everything etc... Have you tried disconnecting all the Front Panel Header leads and jump starting the system, within the case, with a screwdriver - to rule out the possibility of one of the case wires being the issue?

*And all other front i/o case cables etc...

FL630 · 1 Feb 2018 at 13:46

Plec said:
Before you drain everything etc... Have you tried disconnecting all the Front Panel Header leads and jump starting the system, within the case, with a screwdriver - to rule out the possibility of one of the case wires being the issue?

*And all other front i/o case cables etc...

Good plan, I'll try that.

Strangely it does start, fans spin, pump turns on, just no life.

Edit: tried the no-I/O thing. Nothing, starts up, no POST LED's, time to pull the system out again

labcoattech · 3 Feb 2018 at 09:01

If it starts up every time out of the case then it has to be a short. Any pics of the case?

FL630 · 4 Feb 2018 at 22:02

labcoattech said:
If it starts up every time out of the case then it has to be a short. Any pics of the case?

Well this is what I thought, until I rebuilt it out of the case and It wouldn't start. Then it did start, several times very quickly, then when left to rest overnight, it now does.

Decided I'm fed up with it, motherboard is going back under RMA.