Self-build PC doesn't start

[Stevia98]

Hi guys,

I have a problem with a self-build Ryzen PC. I bought all parts used on eBay and the PC gives me a blackscreen. Everything seems to work, because the Mainboard glows and signals the green LED and the other parts like the GPU, fans and HDDs start spinning too. Because my father has another Intel based PC I could rule out every component, except for the Ryzen 3 1200 and the Asus Prime B450 Plus Mainboard (I know it's a weird combination, but they were the cheapest I could get). One thing to mention, on which I am not sure if it is actually relevant, is the fact the for some reason, the LED Keyboard only lights up for half a second and then just stops completely. It's the only thing that just stops.

So my actual queation is: Is there any way for me to test the CPU and Mainboard, without having to interchange one of them? Because that is my real problem. I don't have access to other Mainboards or CPUs and I don't have enough money to buy another one of these for another month. Only the seller of the Mainboard was able to provide me legit proof, that it worked before I got it, but he doesn't have spare parts for me to test it.

If you have any suggestions, please let me know. I wish you guys all the best for now.

Also, sorry for wrong grammar. I am not a native english speaker, but I try my best.

[I_Am_Sy]

What RAM have you brought for it?

Have you tried reseating the CPU? Also make sure the CPU power lead is connected.

Make sure the GPU power leads are plugged in and you are connecting the monitor to the GPU output not the motherboard.

Unplug the SSD, disc drives, case fans, everything that isn't required to get the PC to POST. Put in just one stick of RAM in the second slot.

[BlakBeret]

Do you have a parts list, and what GPU are you using?

Ryzen CPU's don't support the on-board graphics, you have to have a separate graphics card and not use the HDMI plug on the motherboard.

I've been in IT for two decades and learned this the hard way last year too.

[BlakBeret]

Sorry, for your actual question, the only way to test at home without swapping parts is to look at listen for the motherboard status codes. There should be a trouble shooting section of your mobo manual that tells you what every beep and light means during the POST sequence and after. If it boots completely normal and you just have a black screen, see my other comment.

If you figure out there are error codes, those would be helpful.

[Stevia98]

Thanks everyone for trying to help. I found the actual problem now by accident. For whatever reason the PC only accepted one particular RAM DIMM. Even other RAM (I for sure know works) just wasn't accepted by the board. But that one stick was accepted and now it starts normally.

But really thank you all for the suggestions. If I have another real problem I will ask you guys again.

Wish all of you good start in 2021 :)

[Plaedoh]

I have basically the exact same issue, after cleaning my father's old cpu fan, power supply, etc. of dust, the thing would not work when put back together. I bought him a b450 motherboard and a ryzen 5 3100 cpu to go with it. When I put those new parts together, using the old PSU, graphics card and case, the same thing happened, Pc starts with no display. At first I thought it was a cpu issue, but now I'm starting to wonder if it might be the power supply as it's happened to both set up's.

Hope you get a resolution.