Motherboard troubleshooting

MattDX · 21 Oct 2020 at 20:11

Evening. My pc that I built almost 18 months ago seems to have an issue. On boot now the machine doesn’t post and the cpu debug led stays lit. I was lucky enough to grab a cheap compatible pentium and that doesn’t bring it to post either.

With that in mind I’m guessing it’s either the motherboard (MSI z390 pro) or maybe the PSU (I did change it about 5 weeks ago for the upcoming RTX 3070 launch). A few questions come to mind:

Before I buy a multimeter and test the PSU would I even get a cpu debug led if no juice to cpu?
I’m assuming it’s the mb or PSU but am I missing anything obvious?

Alex h · 21 Oct 2020 at 20:35

What psu is it have you got a error code come up on motherboard

MattDX · 21 Oct 2020 at 20:55

Corsair tx750m PSU.
Apologies for my ignorance but where would I see the error code? I just have debug leds.

mickyflinn · 21 Oct 2020 at 21:27

MattDX said:
Corsair tx750m PSU.
Apologies for my ignorance but where would I see the error code? I just have debug leds.

Some motherboards have error codes which is displayed clearly on the motherboard

Slinky69 · 21 Oct 2020 at 21:34

Do you still have the old PSU to try?

MattDX · 21 Oct 2020 at 21:54

No but a friend does so will be trying that on Friday!

mickyflinn · 21 Oct 2020 at 22:11

Have you tried clearing the cmos on the motherboard ?

MattDX · 21 Oct 2020 at 22:21

Took the battery out for a few mins

Quartz · 21 Oct 2020 at 22:32

Check behind the motherboard for fried bugs.

Quartz · 21 Oct 2020 at 22:34

And make sure you have the 8 pin motherboard cable plugged in correctly. At both ends. It's easy to mix up the EPS cable with the PCIE cable.

mickyflinn · 21 Oct 2020 at 22:40

MattDX said:
Took the battery out for a few mins

There should be a clear cmos jumper pins on the motherboard use that as well as taking out the cmos battery and disconnect the power from the wall socket.

MattDX · 24 Oct 2020 at 08:43

Turns out the mb was knackered! My new ASU’s prime a is quite nice too!
As an added bonus this has also fixed my other problem of it not shutting down correctly!
Roll on the 3070 now!
One more quick question - my msi had a nice desktop app that showed fan speed and temps - can’t find anything similar in the ASU’s tools - anyone know of a nice equivalent?

Slinky69 · 24 Oct 2020 at 16:55

Not at my PC to check, but does hwinfo have a fan tab?

eeii · 1 Nov 2020 at 20:19

Asus does have fan control software it’s in the main software suite