Question CPU LED Stays On After Windows Installer BSOD — Ryzen 5 5600 on MSI B550-A PRO

Aug 3, 2025
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Hello everyone,

I’m experiencing a persistent issue with my newly built PC:
CPU: AMD Ryzen 5 5600
Motherboard: MSI B550-A PRO (BIOS updated via Flashback to latest version)
RAM: 2x8GB Patriot Viper 3600MHz cl17 (running at default 2133MHz, no XMP enabled)
Storage:not in
GPU: Gigabyte RX 6600 XT Gaming OC

Problem description:
The system boots up normally, CPU LED lights up briefly during POST, then VGA and Boot LEDs go off, and the PC proceeds to Windows Installer. During installation or after a Blue Screen of Death (BSOD) error in Windows Installer, the PC restarts but gets stuck with the CPU debug LED constantly lit and only the CPU fan spinning. The BSOD I get is Oxc00021a. No display output is received after this point, and the system does not proceed with POST again. Removing RAM causes the RAM LED to light up as expected, confirming the motherboard detects missing RAM. BIOS correctly detects CPU with proper core count and frequency. PSU and cables verified, no bent CPU pins, thermal paste applied properly.

What we know:
BIOS is definitely updated correctly.

The CPU is detected fine by BIOS and POST completes initially, so it’s likely not dead but may have issues during warm reboot or initialization phase.

RAM is recognized but runs at a default low frequency with voltage around 1.19V, which might be borderline unstable for this kit.

The problem occurs reliably after a Windows installer BSOD or system restart.

Removing GPU shifts the LED to VGA, so GPU is detected and seems fine.

Both RAM sticks inserted individually into port A2 do not change anything.

Another motherboard didn't fix it either

Likely cause:
The CPU debug LED staying lit after restart strongly suggests a failure during POST caused by memory initialization instability or CPU initialization failure on warm reboot.

RAM voltage possibly too low for stable operation without XMP, but voltage change hasn’t been tried yet.

Could also be a rare CPU fault causing failure after initial cold boot but stable BIOS POST.

Windows installer and USB drive is definitely not a problem.

Any advice or similar experiences would be greatly appreciated!
Thanks!
 
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if you get a BSOD during the installation process, its only going to be ram or processor or MB. Nothing else is in action until a later step in the install process

Try running memtest86 on each of your ram sticks, one stick at a time, up to 4 passes. Only error count you want is 0, any higher could be cause of the BSOD. Remove/replace ram sticks with errors. Memtest is created as a bootable USB so that you don’t need windows to run it

turn xmp off during the install and see if you can get past where you are.

Is ram on QVL of the motherboard? Did patriot test it with board?

Storage:not in

Its really hard to install windows if you don't have any storage in the PC - where is it meant to install it exactly?

I assume it was at one stage - Might need to wipe the ssd if its got a partial install of windows on it now - I can't tell since I don't know when it failed.

memory controller is on the CPU, could explain light maybe.

only real way to test a Ryzen CPU is to run Prime95 and see if it crashes. The results should show in a text file in the install folder for prime, from memory

instructions may be old, its a while since I used them:
Prime 95 Bootable - https://www.infopackets.com/news/10113/how-fix-bootable-prime95-stress-test-hardware
Prime 95 Instructions - https://appuals.com/how-to-run-a-cpu-stress-test-using-prime95/
 
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Aug 3, 2025
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I ran Prime95 from Ultimate Boot CD. After about 10 minutes, the PC was still running at full speed, but the screen went black and didn’t come back – seems like it froze.
 
Does screen work again after a restart?

seems the results are stored in a temp folder in ram that only existed while PC was on
/tmp/torture-test/torture
So that doesn't really help.

What Power supply are you using?
shouldn't be over heating, its a brand new PC...
What case are you using? What cooler is on CPU?

did you check ram? it shouldn't take long on 8gb sticks, longest part of test is actually when its doing nothing at all. It has one test that checks how well the ram maintains info, and its 15 minutes of nothing... I ran it on my sticks a few months back now. Pc only new itself.
 
Aug 3, 2025
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I tested ram with memtest+ - no errors
My PSU is Zalman MegaMax 500W.
My case is Krux Vako (polish brand)
Cooler is stock Wraith Stealth.
After restart pc works.
 
My PSU is Zalman MegaMax 500W.
@Lutfij do you know this model?

4 year old model.
I can't find a lot on it. It didn't impress anyone on here: https://www.techpowerup.com/286681/zalman-intros-megamax-v2-series-power-supplies

Oxc00021a
STATUS_SYSTEM_PROCESS_TERMINATED (this is an unusual BSOD. I seen plenty in last 10 years, this is rare) - is specifically caused by windows System files, so its an odd one to get on an install. These files shouldn't be corrupted on a clean install, since you say Installer isn't cause. Did you try another USB drive just in case?
If you get same error each time, it could be that windows is partially installed and the files are corrupted.
AS such, I would do this: (need the drive you installing onto in to do this)
Boot from installer

On screen after language choice, pick repair pc, not install

Pick troubleshoot

Pick advanced

Pick Command Prompt

Type diskpart and press enter

Type list disk and press enter

This will show the list of drives currently attached to PC, make note of the drive number of the drive you want to wipe

If Disk 1 is the drive you want to clear, type select 1) and press enter. A message will confirm it is selected

Warning: Diskpart Erase/Clean will permanently erase/destroy all data on the selected drive. Please be certain that you are erasing the correct disk.

Once you sure its right disk, type Clean and press enter

The Command Prompt window will display the message "DiskPart succeeded in cleaning the disk". Close out of the Command Prompt window by clicking the red X in the upper right hand corner.
That will leave you with a blank ssd, try install again.


PSU could cause that as everything relies on the PSU supplying power. It might explain why you got blank screen in Prime as it would have been using a lot of power at that point, and PC have been known to turn monitors off if they running low on power, its not seen as essential to PC.

Wait and see if Lutfij notices this, He might know brand better than I do. Or at least how good PSU is. Its a white label PSU with low efficiency.
 
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do you know this model?
I do, but I have my doubts with that unit as it's labelled with a Zalman. I will always group Zalman, OCZ and Thermaltake's Litepower and Smart units in a corner of a dumpster. User created a similar thread on Tom'sHardware.

Hang on...lemme look further.
+
Yeap, trash!
 
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I would get a different PSU, possibly from Corsair or another better known brand.
Seasonic are another good choice.
Don't want to go mad but it helps to have a good source of power or it can prematurely kill other parts

I haven't been on Tom's for a while.
 
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Aug 3, 2025
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Guys I tried another power supply from a friend (600 or 650W) and it made no difference. The first thing that came to mind was the PSU, so I tried another one. But since that didn't help, I'm left with the processor, which I can return today. What do you suggest I do?
 
What is the new PSU?

If its easy enough, try swapping CPU.
I don't like not knowing the actual cause, swapping parts can get expensive if you not sure what cause is.

i would suggest something like this is a good PSU to start from:

what are the ram codes? it could just as easily be an incompatability there too. Just cause you didn't BSOD doesn't exactly count them out.
 
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What is the new PSU?
it was a PSU from their prebuilt, I don't know what exactly this PSU is, neither does he.
what are the ram codes? it could just as easily be an incompatability there too. Just cause you didn't BSOD doesn't exactly count them out.
On the ram stick:
PV5416G360C7K
9DE00229
On the box:
9DE00229-PVS416G360C7K

BTW I can still return RAM, PSU, and CPU.

i would suggest something like this is a good PSU to start from:

Do you think the Deepcool PF500 would be a better option? I did some research before buying, and 500W should easily handle my system.
 
MSI only tested one lot of Patriot ram and it wasn't yours, and looking at https://cdn.prod.website-files.com/...492e14b5d_Patriot_Viper_DDR4_QVL_list-MSI.pdf there is a lack of any B550 tested
ceMeUgJ.jpeg

Your ram is final column

So I would suggest getting ram tested on board.

Hard to find reviews on any Deepcool as they banned in USA, but as I have 2 of their Air coolers, I know they can make good stuff.
 
Aug 3, 2025
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From what I understand, even if it's not causing the problem, the Zalman PSU needs to be replaced. The Deepcool one seems fine. However, I don't quite understand what you mean by "RAM tested on board.". According to memtest+ it works fine. Should I return it too? I also had this problem on my previous Gigabyte board and the twin RAM (PVS416G360C8K) is supported.

@33P4BLO If you go through the PSU tier lists I've linked above, the PF series units less than 750W are trash - you're just replacing your existing PSU with another one from the same stack = you're not getting an improvement.
I'm on a budget, and I don't care about the best power supply, especially if it's modular. What should I choose?
 
the timings of the ram could be causing the errors. Just because it passes memtest doesn't mean it can't be causing errors.
Motherboard makers test the sticks to make sure they work. Patriot also do from their end.
Neither tested your ram with that motherboard.
misbehaving ram will cause BSOD.

Deepcool don't even make that model anymore.

Better to listen to Lutfi and get a better PSU. Buying a cheap PSU doesn't save you anything if other parts die.
 
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I'm on a budget, and I don't care about the best power supply, especially if it's modular. What should I choose?
I don't know where you're located, nor do I know your budget nor do I know what you have access to. If I suggest something you don't have access to, we're just going to waste time going back and forth. Along those lines I'm trying to stop you from buying into another dumpster fire PSU. No one said you should pick the best PSU out of the bunch but you also need to keep in mind that a PSU is considered the heart of the system. If and when it has a heart attack, a badly built PSU will take everything out with it.

A quality unit will quietly pass away, without the other parts being hindered. Ask me and the other folks around the word how I/we know...?

You can also do the math yourself, a cheap PSU that kills everything or a reliably built unit that doesn't harm your other investments?

I hope you're able to resolve the issue. Good luck!
 
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I'm not very knowledgeable when it comes to computer components (as you can see). I already know I should replace the PSU with a reliable one. As for RAM, should return it and find a replacement that's on MOBO's QVL? And as a precaution, should I also replace the CPU with the same one from another seller?
 
I also don't know what you can get but can you get corsair ram? most motherboards work with it and just putting their name into MSI site shows they tested an entire page of their Ram.
https://www.corsair.com/us/en/p/mem...ram-3600mhz-c18-memory-kit-cmt16gx4m2c3600c18 is about only 3600 on list. rest is 3200

Your CPU is the 2nd selection type on here, not 5X00GE as they are APU, not CPU

How long you got on return on CPU?
Its possible its all the Ram.

I have had PSU go bang on me - but it was 6 years old. It took my GPU & windows install with it.
Cheap PSU killed about 3 of my HDD as they were new drives each time.

So yes, PSU can cost more than their cost
 
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I also don't know what you can get but can you get corsair ram? most motherboards work with it and just putting their name into MSI site shows they tested an entire page of their Ram.
https://www.corsair.com/us/en/p/mem...ram-3600mhz-c18-memory-kit-cmt16gx4m2c3600c18 is about only 3600 on list. rest is 3200

How long you got on return on CPU?
Its possible its all the Ram.
It doesn't have to be 3600MHz; 3200MHz is definitely enough (if it's CL16). I'm on a budget, so RGB isn't a priority. I need to send the CPU in by Thursday, and if I can, I could have the RAM by tomorrow.

I have had PSU go bang on me - but it was 6 years old. It took my GPU & windows install with it.
Cheap PSU killed about 3 of my HDD as they were new drives each time.

So yes, PSU can cost more than their cost
Okay, I'm definitely returning the PSU.
 
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https://www.corsair.com/ww/en/p/mem...00mhz-c16-memory-kit-black-cmk16gx4m2e3200c16
Corsair tested this against your board
No RGB
Cheapest Corsair ram really
Put make/model in here if you want other choices.

I went from not caring what PSU I had to making sure its a good model. You can go overboard but having slightly more than you need is better than not enough.
I don't want to rush into something stupid. Do you think I should return the CPU, PSU, and RAM just in case, and choose better options?
 
CPU might be fine. It seemed to run Prime95 okay even if PSU turned the screen off.
Problems could just be PSU & Ram related. I would return them
I had a 3600 before, the 5600 should be fine. It happens but CPU generally aren't the first thing I blame.

You have to be unlucky to have 3 bad items
 
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CPU might be fine. It seemed to run Prime95 okay even if PSU turned the screen off.
Problems could just be PSU & Ram related. I would return them

You have to be unlucky to have 3 bad items
I'm just afraid that the time to return the CPU will run out, I'll buy a new PSU and RAM, and then it will turn out that it's the CPU's fault.
 
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You should have a year warranty on it. If you can prove its bad, you RMA it with AMD and they replace CPU.

If it is easy, just swap now if it make you feel better, but it might be fine.
"The serial number entered has been identified as a genuine PIB processor and it is covered under AMD Processor in a box (PIB) three Year Limited Warranty terms and conditions."
I don't know if I'd be able to prove damage to them, although EU law certainly helps. Maybe for peace of mind, I'll return this one (I'll only lose the shipping cost) and once I have the right PSU and RAM i will order another Ryzen?