Question Asus B550 motherboard, 1 long 3 short beeps

[ZephanUnbound]

So, I recently decided to upgrade my old PC from 2015. Here are the specs of the new parts:

Motherboard: Asus B550-Plus AC-HES
PSU: Reused from old build- 750w
CPU: Ryzen 5500
RAM: Teamgroup 16 GB (2x 8) DDR4 3200
Storage: 1TB PCIe 3.0 SSD + 1 TB 7200 RPM HD
GPU: Reused from old build temporarily (MSI GeForce GTX 950)

After I finished installing everything in my old case, I turned it on and got a black screen only. All fans spin-up from PSU to CPU to GPU to case fans, keyboard and mouse light-up, lights on I/O panel on back of motherboard cut on, but no video signal, just a black screen followed by my monitor saying "No signal detected" and automatically going into sleep mode. Bought a POST code speaker and plugged it in, and I'm getting 1 long beep followed by 3 short beeps. Google says that for an Asus motherboard, 1 long and 3 short means a video card error, which checks out with what I'm experiencing with no video. Because my CPU has no integrated graphics, I have no alternative but to use my old GPU, since I'm waiting on a good bargain for my GPU upgrade.

I've tried reseating the graphics card in my top slot 3 times now, as well as seating it in 2 other slots, same beep codes and lack of video signal each time. I've also tried reseating my RAM in different slots and tried each stick 1 at a time in 2 different slots each. What should be my next step? CMOS battery removal?

The Asus website says that the 3 beeps error code I'm getting could mean that my PSU isn't supplying sufficient power through my PCIe cable to the GPU, so maybe my old PSU just isn't up to snuff and isn't supplying my card with enough power? Should a new PSU be my next step, or do you think the motherboard could be bad or that I damaged my GPU somehow while removing from my old motherboard and putting it in this new one the first time?

 

[Lutfij]

PSU: Reused from old build- 750w
750W is the advertised wattage of the unit. What is the make and model of the unit? How old is the PSU?

https://www.asus.com/motherboards-c...elpdesk_cpu?model2Name=PRIME-B550-PLUS-AC-HES
According to this CPU support list, you will need at least BIOS version 2423 in order to work with the Ryzen 5 5500. can you verify using the stickers around your motherboard's PCB to identify what BIOS version was bundled with the board? By my search BIOS version 2423 is the second BIOS release for that board.

Conversely you can use the ASUS Crash Free BIOS 3 option;
https://dlcdnets.asus.com/pub/ASUS/...C-HES_UM_WEB.pdf?model=PRIME B550-PLUS AC-HES
page 2-4, and see if you can recover the BIOS.

 

[ZephanUnbound]

The PSU is quite old, an Ultra LSP-750. I will probably replace it, I was planning to reuse it due to it being reliable for so long and to save some money, but I realized when putting my new parts in that it only has PCIe 6 pin cables and most modern GPU's need at least one 8 pin cable, so I will need to upgrade before I buy my new GPU either way. 6 pin should be plenty for my old GeForce 950 though, it only takes a 6 pin cable and the same PSU was powering the card fine on my old motherboard.

Assuming the Bios version is on the sticker between the CPU and RAM slots, the bios version is 2604.

 

[ZephanUnbound]

So I was going through the checklist on Asus' support site today and realized that the cheap plastic cooler backplate that had came with the motherboard had some of the plastic holes for the screws sheer off, so my Wraith Stealth cooler was partially loose. Just bought a metal cooler backplate from Amazon that is supposed to have 1 day shipping, so I will reinstall the cooler tomorrow and hopefully that will fix it.

I'm still not sure that is the problem though, Asus site says 1 long and 4 short beeps is for CPU issues, and I'm pretty sure I have been counting 1 long and 3 short. I will post an update after trying again with my CPU cooler reinstalled.

 

[ZephanUnbound]

So I put in the new metal backplate and resecured my Wraith Stealth cooler. Still getting no video on boot and 1 long + 3 short beeps. What should my next step be? New PSU, New graphics card, both?