Question No POST without "b2" code ?

[ETruth]

I am having a lot of trouble with this PC I have. I built it a while ago, and ever since a few weeks after I bought it, I have been having a pretty major and annoying problem getting the thing to even POST. The PC will not boot unless I see the "b2" code appear on the Q-Code readout. This means that I have to power cycle the computer, usually for around 10-15 minutes, in order to get my PC to boot. As you can imagine, this is incredibly frustrating. I have built a lot of computers for friends and never ran into this issue. I should mention that once the PC does boot, it runs fantastically. I am not overclocked at all, as I am trying to fix this problem first, and the only thing changed in the BIOS is that the memory is running on an XMP Profile. Everything else about this system is at optimized defaults. I have all of the expected performance and I have never once experienced a blue screen or crash on this PC. I have been through 2 motherboards and 2 power supplies trying to diagnose this problem, I have disconnected all non-essential hardware, tried booting with just one RAM stick, etc, and I am just out of ideas. I am willing to try anything, so please help if you can.

Specs:
Ryzen 9 3900X
EVGA RTX 2080 Super XC Ultra Gaming
Corsair Vengeance RGB Pro 32GB (2x16) (On Motherboard's QVL)
Gigabyte B550 Aorus Master Motherboard (BIOS Version F12)
Crucial P2 500GB NVME SSD
Seagate Barracuda 2TB Hard Drive
EVGA SuperNOVA 850 G5 850W PSU

Accessories:
Corsair H100i Water Cooler
Corsair LL Series 120mm fans

Thank you to anybody who is able to help!

 

[Ralston18]

What case are you using?

Have you been able to check the case's power switch and reset switch?

Ensure that they are fully and firmly connected.

Then, if necessary test the switch for connectivity. Could be a faulty switch.

Next would be to test the PSU. Do you have a multi-meter and know how to use it? Or know someone who does?

https://www.lifewire.com/how-to-manually-test-a-power-supply-with-a-multimeter-2626158

Not a full test because the PSU is not under load. However any voltages out of tolerance may be a clue as to what is happening.

Any differences if PSU is cold, warmed up, or even "hot"?

 

[ETruth]

What case are you using?

Have you been able to check the case's power switch and reset switch?

Ensure that they are fully and firmly connected.

Then, if necessary test the switch for connectivity. Could be a faulty switch.

Next would be to test the PSU. Do you have a multi-meter and know how to use it? Or know someone who does?

https://www.lifewire.com/how-to-manually-test-a-power-supply-with-a-multimeter-2626158

Not a full test because the PSU is not under load. However any voltages out of tolerance may be a clue as to what is happening.

Any differences if PSU is cold, warmed up, or even "hot"?

Thanks for the reply! I have the Fractal Meshify C. The power and reset switches are fully connected, yes. I have tested the power supplies both times as I am an EE student, and I have found no faults with the power supply. The values are within normal spec between +- 5%. And I am aware that it isn't under load, but there would most likely be more issues with transient loads if the power supply was at fault, and like I have said, there is absolutely no performance loss, or crashing like you would probably see with a faulty power supply. Both of the power supplies that I have bought have been very good ones with great reviews, and they are both from different companies, so it is unlikely that both of them are bad. I have noticed that I can turn the computer back on 100% of the time without any issues right after I shut down the computer, but if it is off for the night for instance, then I have the same problem

 

[Ralston18]

CMOS battery?

You tried two motherboards - correct?

Did you happen to use the same CMOS battery in each motherboard?

 

[ETruth]

CMOS battery?

You tried two motherboards - correct?

Did you happen to use the same CMOS battery in each motherboard?

Yes, I went from a brand new Asus ROG Crosshair VII Hero (X470) to a brand new Gigabyte B550 Aorus Master, which is currently in the PC. Upon installing the Gigabyte, I replaced the CMOS Battery with a brand new battery that I had bought with the motherboard as I had read that sometimes the ones they ship with fail. Haven't had nay problems with BIOS at all, so I don't believe the CMOS Battery is dying

 

[Ralston18]

Next time you boot up go int POST and configure POST to be as verbose as possible.

This is, you want POST to display everything it is doing and the end results.

Watch POST on the initial boot up (when the system does boot) and try to spot some difference in the POST results or pattern between failing to boot and successfully booting.

One thought that I have is the problem could be temperature related. Fails when the system is cold/cool but succeeds once warmed up.

Some connection not being made until warmer and expanded enough to make contact.