Solved No post on newly built PC? Help needed!

Hello!

Specs:

CPU: Intel Core i5-9400F

RAM: Two 8gb sticks from a HP prebuilt

PSU: Corsair CX600

GPU: Nvidia RTX 2060

Motherboard: ASRock Z390 Pro4

All the components have been tested in another system except the motherboard. I don't have another compatible CPU. If I don't have the RAM sticks in A1 and B1 the system seems to boot but doesn't post. The fans turn on and the GPU lights turn on. There is no display at all. I am plugged into the GPU and not the motherboard. After some time (>1min) the system turns off again.

I have reseated the CPU, RAM and GPU. I have reconnected the 24-pin, CPU 8-pin and GPU PCI 8-pin connectors. Twice. I have tried a single stick of RAM in each slot at a time and all 2-stick combinations.

Any suggestions would be extremely appreciated as I no longer have any ideas!

Thank you a ton in advance!

Bruce said:

which parts are old and which are new?
can you supply the full specs of that memory, make/model/speed?

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The memory is Samsung m378a1k43cb2-ctd and it should be running at 2666. Only the motherboard I haven't previously used in another system.

Bruce said:

will need to check the Asrock QVL to check if the Samsung memory is compatible.

so the mobo hasn't been tested in another system, but what about the other components in your PC, the memory was from another PC, what other parts are pre-loved?

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Literally everything else has been pre-used by me.

Samsung M378A1K43CB2-CRC is in the QVL. The last three letters are different from my sticks, though. (CRC vs CTD)

The thing is that I can't get to BIOS: there is absolutely nothing on screen after shorting the power pins

Update: Got my hands on an internal speaker and the error code is three beeps and a long pause. Then it starts over again.

Fixed it! Reseated the CPU and RAM once more and plugged in the HDMI cable! I had accidentally removed it when reseating the GPU. Massive facepalm... Well, I'm glad there isn't a hardware problem.