New AM5 build without POST, no diagnostic lights, no GPU power?
New AM5 build without POST, no diagnostic lights, no GPU power?
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
These are accurate points. Did you link the monitor to MoBo? If not, please do so and check if there’s any difference.
If it still doesn’t work, the likely causes are CPU, MoBo, RAM, or PSU.
A mediocre quality PSU is present—specifically Tier B.
For a gaming rig, a proper PSU should be Tier A.
PSU tier list: [link]
Tier A is suitable, while Tier A+ is better.
My setup uses three PCs all powered by Tier A PSUs: Seasonic PRIME 650 Titanium (A+), Seasonic PRIME Ultra 650 Titanium (A+), and Seasonic Focus PX-550 (A). Full specifications with images are available in my profile.
Consider testing with a second, compatible system to confirm the problem.
Using MoBo directly could be risky—since a dead-on arrival is more probable than CPU or RAM failure.
However, RAM or CPU issues are also possible.
To be certain, you’d need a second, compatible machine for testing the CPU and RAM.
Bypassing MoBo means installing a known working CPU and RAM into it, rather than using the ones you just purchased without knowing if they function.
Few people have access to a second compatible system, so the next best step is to take your PC to a repair shop for diagnostics.
Welcome to the forums, newcomer! Are you managing to keep the processor cool? Have you checked the CPU's socket for any bent or damaged pins? You might want to place the cooler on the CPU IHS while the system is mounted sideways, as excessive pressure can cause pins to bend and prevent a successful boot. Keep in mind, don't downgrade your BIOS, as this could result in a non-functional motherboard.
So I believe I’ve finally figured this out without realizing the real issue was my own mistake.
I moved the PSU and GPU into my old PC, and the GPU turned on clearly, but there was still no output.
I looked at the monitor and joy of joys, checked the HDMI cable, it wasn’t fully seated. After fixing that, I tried the new PC without the GPU and reached the BIOS, which I think it had been using most of the time.
Once I reinserted the GPU into the new PC, it worked properly again. I’m not sure why the GPU didn’t get power initially—maybe it wasn’t fully seated or something—but all my troubleshooting efforts failed because of the HDMI connection and removing the GPU early on.
The BIOS is now up to date and everything else is wired back in. The final test and Windows installation will be done tomorrow.
Thanks for your help,
And just to reassure you, I do have a CPU cooler, though I didn’t think it was important 😊
When I replied, I thought you were careful enough to verify every cable connection and ensure they were properly seated.
But I strayed from the topic.
Looking ahead, please double-check all cable connections whenever problems occur again. A loose HDMI cable is sufficient to prevent any display issues.
It’s great to hear your issue has been resolved and your system is working smoothly.