Computer will not post on cold start

[RPHelp]

I built this PC a little over a year ago, and it's been fine. I don't use it much, mostly stick to my laptop. But a couple weeks back, it wouldn't POST. After messing around with it – unplugging stuff, holding the power button – I found that if I hold the power button and flip the power supply switch on and off, it boots up. Then it runs fine for hours.

 

The next day, or shortly after, it wouldn't POST. I gave up and used my laptop. But then, after a 5-10 minute delay, it booted normally, having only pressed the power button. Later that day I updated BIOS and turned off computer didn't use it over weekend.

 

Monday morning, my computer failed to POST when I needed it for work. I tried waiting for it to boot, but after a frustrating 25 minutes, it remained unresponsive. Attempting my previous workaround—holding the power button while toggling the power supply switch—also failed. Further troubleshooting involved clearing the CMOS and testing RAM modules individually in slots A2 and B2, all to no avail.

Recently, a new issue arose: the computer would take an excessive amount of time to POST, and when it did, it would get stuck with a yellow LED on the motherboard. I resolved the yellow LED issue by downgrading the BIOS and enabling 'Memory Context Restore' in the BIOS settings. Initially, this appeared to fix the problem, as I was able to shut down and restart the computer without issue, and it even booted normally the following day. (YAY ISSUE IS FIXED) and I was wrong it didn't.

 

However, after leaving the computer untouched for 2-3 days, it once again failed to POST. I tried unplugging it from the wall and leaving it disconnected overnight, but this did not resolve the issue. The computer now only POSTs after either holding the power button while toggling the power supply switch or by pressing the power button and waiting for an extended period, which can range from minutes to hours. Another thing If the computer is running, I can immediately power it off and back on using the power button without issue. However, if it's left off for several hours or a day, it won't POST unless I use my unusual workaround

 

Here's the weird part: once I actually get this thing to boot, it's rock solid. I work from home two days a week, and I'll use it for hours with zero problems. No crashes, no heat issues, no reboots, no random shutdowns nothing. I'm actually using it right now, CPU's at 42°C, GPU's at 41°C, running great. It's just getting it to turn on that's a issue.

 

My specs:

• Motherboard: TUF GAMING B650-PLUS WIFI

• CPU: Ryzen 9 7900X

• RAM: G.SKILL F5-6000J3636F16GX2-FX5 AMD EXPO 32GB (2 x 16GB)

• GPU: RX 7800 XT

• PSU: CORSAIR RM750e

 

 

[leclod]

First thought : change psu.

But wait...

First I'd replug/reseat everything carefully, also on psu side.

If you can, do it minimal, mobo outside the case on plain cardboard.

 

[johnt]

Change the battery on the motherboard. It might be dead and your CMOS might be losing its mind trying to stay current. You might be stuck in memory training every time you try a cold boot which manifests as "not posting."

[RPHelp]

14 hours ago, leclod said:

First thought : change psu.

But wait...

First I'd replug/reseat everything carefully, also on psu side.

If you can, do it minimal, mobo outside the case on plain cardboard.

 

 

I'm about remove GPU and just rewire everything and run on board GPU and see if that helps, that way I have everything repluged and stuff. but I didn't touch computer at all and it just did this so not sure if redoing wire gonna help as it was running fine over a year one morning just stopped working like it supposed too 

 

14 hours ago, johnt said:

Change the battery on the motherboard. It might be dead and your CMOS might be losing its mind trying to stay current. You might be stuck in memory training every time you try a cold boot which manifests as "not posting."

I was thinking it might be battery too but it does hold my BIOS settings so but I did replaced cmos battery 2032 today didn't help

[RPHelp]

Update:
 

So, it’s not the power supply. I found my old build and swapped in the power supply (EVGA SuperNOVA 550 GS). I know it’s only 550W, so I removed the GPU (RX 7800 XT) and am just using the onboard GPU for testing. with that power supply it does same. 

 

Unfortunately, my old build uses DDR4 while this one uses DDR5, so I can’t swap the RAM to test that.

 

After messing around in the BIOS today, I downgraded to version 3072, which is the version that previously allowed me to get it to post/boot using my method (pressing the power button while toggling the power supply switch). But now, that method doesn’t work anymore, and I’m stuck on the yellow light. 

 

pressing the power button does nothing—no fans, no QLED check light on the motherboard, nothing. The only light I see is a blinking green light near the BIOS flash. when I use the method (pressing the power button while toggling the power supply switch), the machine does post, the fans spin, and the motherboard light turns yellow.

 

Also, none of the drives are plugged in—only the DP cable is connected. (no usbs, no keyboard, no mouse nothing) 

[johnt]

Are you able to RMA your motherboard under warranty? It seems like there is an electrical gremlin somewhere in there.

[Mike340]

I'm having this exact problem with a Micro Center Bundle - Ryzen 7 9700x, Gigabyte B650 gamer X AX V2 (rev 1.2) [bios flashed to F33b], Corsair 32gb 6000 ddr5 (2x16) rgb.
I have returned two of these bundles already for the same reason and I am on my third one, and it is still doing the same thing.
PSU: Corsair TX650W, Radeon RX 570 4gb (Nvidia 1660 Super)

 

When it boots, it runs amazing and have no problems but refuses to boot after shutting down via windows (Win10 Pro 64-bit). I have tried changing PSU and GPU but still won't boot after shutdown unless I clear cmos or remove the plug for at least 10 mins.

I've been building computers since the late 90's and have never had this kind of B.S. from any build before, regardless of parts. Heck, the first system I built was from parts I found in the trash back in the old ISA board days.

This one has me stumped and I hate to keep replacing the whole bundle because they don't take individual parts back. I'm just about done with this whole AM5 mess and try AM4 even though it's a dead system now at least it's proven.

I've been running my FX8350e on Gigabyte 970 for nearly a decade and have never had any problems with it, but it's long in the tooth and I really need an upgrade.

I have a new PSU arriving today and a new cooler just to make sure I troubleshoot every possible angle but I have little hope of it fixing the problem.

[Mike340]

Update:
OK, I swapped out the PSU again and, as illogical as it is, it worked...flawlessly.
I installed a brand new 850w PSU even though that is way more power than it should ever need.

 

I don't understand why the older Corsair 650W PSU (80+ Bronze) was the problem. I swapped it with the PSU from my wife's rig which is exactly the same Corsair but ended up with the same problem. These power supplies are from around 2010 or so (iirc) but the FX 8320e is a 95W TDP chip...so the new rig actually draws less power.

I don't know if there was some new manufacturing change to PSUs that makes the new platform require them or what? I'm not that savvy about PSU power delivery needs.

The new PSU is a Poinwer P-850 Modular PSU (80+ Gold) I got from Amazon

It has a 72A 12v Rail.
The Corsair has a 53A 12v Rail. -Not sure if the amperage makes a difference here as far as the board needs are concerned, but as unexpected as it was, it worked.
If anyone can enlighten me I would love to know why this could make a difference.

I am tempted to try a new 650W PSU just to see if it's the actual wattage or just being new that makes a difference.

Whatever the magic is, at least it works. It starts and shuts down quickly and restarts exactly as it should.

 

One thing I did notice, my external USB HD would stay lit when the power was off using the Corsair, but it's completely off using the new Poinwer...
So was the Corsair not actually powering down? I guess that's why I had to disconnect it for at least 10 mins...maybe the caps are not discharging as they should?

But weird that it was the same with a second unit subbed in.


It doesn't make sense (at least to me) but it worked.
I should have just started with a fresh build from the start instead of trying to just upgrade and save a few bucks, because with the return trips and lost time, I actually ended up spending way more than a fresh build would have cost.

I hope this helps someone else experiencing the same problem.

 

PS: I did not change the cooler after all, just the PSU.