New build, can't get stable power or video out, bad motherboard?

[danieljmolloy1]

Parts:

• 
  CPU - Ryzen 5 1600
  Mobo - Asus - PRIME B350-PLUS
  RAM - Corsair - Vengeance LPX 16GB (2 x 8GB) DDR4-2666
  PSU - Corsair - VS 550W

So I’m building a new PC with some parts salvaged from my old one (PSU, GPU and SSD are old, rest is new). When I put everything together and powered on, I discovered that I was not getting a stable power supply, the power was switching off briefly every few seconds.

I tested my PSU with the paperclip test and it was completely stable over several minutes. Also this PSU is only ~1 year old and worked fine in my old build, so it’s probably not the culprit.

Next I stripped everything out except the Mobo, CPU, and PSU. Now when I switched it on the power was stable. However I could not get a video output from the motherboard (I tried hdmi and VGA). Should I have been able to get a video output without any RAM installed?

Next I plugged in a RAM stick, and when I powered on I was again getting the power switching off every few seconds. I tried both RAM sticks separately, and I tried all 4 RAM slots, all with the same result. Here’s a video of the power cycling. When there are no RAM sticks inserted the led’s are stable and do not flicker.


At this point I’m thinking it’s a dodgy motherboard. Any ideas?

UPDATE: My Mobo didn’t come with a speaker, so I salvaged the one from my old build and breadboarded my Mobo (to rule out case issues. Results - With no RAM, there are no beeps. With a RAM stick installed, there is a loud beep (POST?), a pause, then a long beep and 4 short beeps. This table says that this pattern indicates a hardware component failure.

How do I know if the problem is the motherboard or the RAM?

 

[alexoiu]

I suspect that you're not inserting correctly the RAM modules. Some require more force. Check some videos on youtube for how to.
Then your board and CPU need a graphics card and monitor connected to it for video. The onboard does not work.