Question System does not POST. I feel like I have tried everything!

[nickfoster6191]

Good morning/afternoon/evening,

I have been having intractable problems with my system for 2 months and I am running out of ideas. I would be very grateful for your input.

I bought the motherboard, CPU, cooler and RAM in February 2019 from Scan.co.uk and built this system with additional parts from my previous system:

Intel Core i7 8700K Unlocked Coffee Lake CPU
Arctic Freezer 11 LP Low Profile Intel CPU Cooler
Asus PRIME Z370-P II
Corsair DDR4 4GB Value Select RAM x2
Kingston Technology SA400S37/120G SSD A400 120 GB Solid State Drive
Gigabyte Nvidia Geforce GTX 780ti OC Version
Windows 10

I had no problems assembling the system and it ran like a dream for 10 months.

Without warning it crashed mid-game and would not switch on again. I did the paperclip test on my PSU (not 100% sure I did this right) and determined that the PSU was broken.

I installed a new PSU - 750W Corsair RM750i, but this had no effect.

I tried circumventing the power switch, minimal config, CMOS reset and removing RAM modules but this had no effect.

I RMA'ed the motherboard and Scan tested it and found no problems.

I RMA'ed the CPU and the RAM and Scan tested it all together and found no problems.

I have all the parts back now and I still can't get it to POST. In minimal config the PSU fan flickers on in ~5s intervals and so does the monitor. The CPU fan flickers on only when I switch the power off. There is a video of this here:

View: https://youtu.be/i52nJQVIdDo


Interestingly before I sent the parts off for RMA the system behaved slightly differently: both the PSU and the CPU fans flickered on at the same interval rather than just the PSU.

I would be very grateful for any suggestions!

 

[mm1532]

I know this is a silly thing to say, but have you tried to check and see if all of your power cables and ram are pushed in properly? I know a few builds that i did before had the same issue, and it was because either the CPU power connector/24 pin connector wasn't pushed in all the way. Give them some force. They won't break.

 

[EndEffeKt_24]

I had a pretty similar problem once and it came back to be a slightly lose Ram module.

 

[nickfoster6191]

Thanks for the ideas. I have triple- and quadruple-checked that everything is seated properly and it's still behaving the same way

 

[EndEffeKt_24]

Alright. Time to strip the system down I would say. To rule out as much components as possible I would rake the system apart and asemble the most barebone version on top of a cardboard box.
Cpu, mobo, 1 stick of Ram, maybe boot drive (not needed to post) and psu.

If it turns on the faulty part is somewhere in the other pile and I would start with switching in the other sticks of ram.

If it does not start the part in question is right in front of you. Start with switching to another ram slot. If it aint working try another single stick of ram. They cant be all faulty.

Have a nice sunday my friend.

 

[nickfoster6191]

Update: I gave up and took it to a professional because I don't have the spare parts to do extensive testing myself. Turns out the PSU was DOA