Question New AM5 build no POST, no diagnostic LEDs on, no GPU power?

[aedwards00]

I've just completed a new build and am now tearing my hair out at its failure to POST.

Components:
Motherboard: ASRock PG Lightning B650 with a sticker saying 3.10
CPU: AMD Ryzen 9 7900X
RAM: Patriot Viper Venom 2x16GB CL30 6000
PSU: MSI MAG A850GL PCIE5
GPU: Zotac GeForce RTX 5070ti SOLID CORE OC

Symptoms:
On first powering the system on, all case and CPU fans spun up and the POST diagnostic LEDs on the motherboard illuminated for some time as expected, before eventually all extinguishing. At this point I had the monitor connected to DP1 on the GPU but saw no output. Interestingly (maybe?) the GPU fans didn't spin at all, and there's no sign of the "power safety LED" that the GPU claims to have (should be green if the power lead is connected correctly, red otherwise). Subsequent power on attempts have the same end result but with less time waiting for the LEDs to extinguish.

What I've tried, roughly in order:

• All other ports on the GPU (DP and HDMI), plus the HDMI on the motherboard - no output on any.
• Reset the CMOS using the jumper - returned to an longer LED phase on the next power on, no other change.
• Disconnected all drives from both the PSU and motherboard - no change.
• Disconnected the GPU from the PSU - no change.
• Reseated all power leads - no change.
• Removed the GPU entirely - no change.
• Removed 1 stick of ram (tried in both A2 and B2) - no change.
• Removed all RAM - CPU and DRAM POST lights stay illuminated, which I guess is expected, perhaps not the CPU one?
• Updated the BIOS to 3.30, the latest available - longer LED phase on next power on but otherwise no change.
• Downgraded the BIOS to 1.03, the version that was validated against my CPU - as above.

To confirm that I'm (hopefully) not doing anything dumb with the PSU, I've been using the following (when connected)

• 24 pin ATX (16+8 at the PSU) to the motherboard
• 2x 8 pin CPU to the two CPU power ports on the motherboard
• 12v 2x6 to the GPU

I'm really at a loss to what the problem is to know what part needs replacing - the fact the LEDs all go off seems to suggest that no faults are being detected and everything should be working? I'm slightly suspicious of the lack of the power safety light on the GPU, but if that were faulty I'd expect things to work with it out of the equation. For what its worth there weren't any obvious signs of damage to pins in the CPU socket or any other component.

Any help would be much appreciated

 

[Aeacus]

To confirm that I'm (hopefully) not doing anything dumb with the PSU, I've been using the following (when connected)

• 24 pin ATX (16+8 at the PSU) to the motherboard
• 2x 8 pin CPU to the two CPU power ports on the motherboard
• 12v 2x6 to the GPU

These are correct.

Removed the GPU entirely - no change.

When you did this, did you connect monitor to MoBo? If not, do that and look if something changes.

If still no dice, following (or all of them) are dead: CPU, MoBo, RAM, PSU.

PSU: MSI MAG A850GL PCIE5

Mediocre quality PSU. Tier B.

For proper PSU for gaming rig, Tier A is proper.
PSU tier list: https://docs.google.com/spreadsheet...JWkc/edit?pli=1&gid=1973454078#gid=1973454078

Tier A- will do too, while Tier A+ is preferred.
(My 3x PCs are solely powered by Tier A PSUs. Namely, i have Seasonic PRIME 650 Titanium (Tier A+), Seasonic PRIME Ultra 650 Titanium (Tier A+) and Seasonic Focus PX-550 (Tier A). Full specs with pics in my sig.)

So, try with 2nd, known to work, good/great quality PSU.

I'm really at a loss to what the problem is to know what part needs replacing

As of what else can be the issue, i suspect DOA MoBo. Since Dead On Arrival MoBo is far more likely chance than DOA CPU or DOA RAM.
Though, it can be RAM or CPU issue too.

To know for sure, you need 2nd, compatible system, where to test out CPU and RAM. Testing MoBo means that you put known to work CPU and RAM into it, and not the ones you just bought and have 0 idea if they even work.
Not many people have 2nd, compatible system at hand, so, 2nd best option is to haul your PC to PC repair shop and pay for diagnostics.

 

[Lutfij]

Welcome to the forums, newcomer!

How are you cooling the processor? Have you inspected the CPU's socket for any bent or broken pins? You can try resting the cooler onto the CPU IHS while the system is on it's side as there have been instances where too much mounting pressure on the CPU's socket caused some pins to bend and thus a no-POST scenario.

One thing to note, please don't downgrade your BIOS as that can lead to a bricked motherboard.

 

[aedwards00]

Ergh so I think I have finally resolved this without knowing exactly what the problem was beyond my own incompetence.

I transplanted the psu and gpu into my old pc and the gpu powered on in an obvious way, but I still had no output.

At this point I checked the monitor and joy of joys the hdmi cable wasn't fully seated. Having sorted that I tried the new PC again without the gpu and reached the bios, which I suspect it had been doing most of the time.

After adding the gpu back to the new pc it then powered up fine. I don't know why the gpu didn't originally have power,maybe not fully seated or something, but all my troubleshooting was in vain because of the hdmi lead and having removed the gpu early in the process.

Bios is now back up to date and everything else back wired up, final test and installing windows is a job for tomorrow.

Appreciate the assistance,
and just to reassure you I do have a cpu cooler but didn't think it was likely relevant which one 🙂

 

[Aeacus]

At this point I checked the monitor and joy of joys the hdmi cable wasn't fully seated.

When i wrote my reply, i assumed you were diligent enough to double check all cable connections and making sure they all were fully seated.
But i digress.

Moving forwards, do double check all cable connections when issues should arise again. Since loose HDMI cable is enough for not seeing any image.
Still, nice to hear that you got your issue solved and system up and running.