[Help] B450 Tomahawk MAX + Ryzen 5800X — CPU debug LED, no POST even after BIOS flash

Hardware & Gaming
1

Specs:

Ryzen 7 5800X

MSI B450 Tomahawk MAX

Corsair Vengeance 8 GB × 4 (3600 MHz CL18)

Nzxt c1000 gold psu,

PC was working fine for a long time, then suddenly started shutting down and restarting on its own. Happened 6 times in a day ,tried everything that was possible through os or software couldn’t find any issues ,so i decided to check psu connection and replugged it all,

After that, it refused to boot — fans spin, RGB lights up, but the CPU debug LED stays solid red.

Here’s what I’ve tried so far:

Reseated the CPU twice, cleaned and repasted.

Cleared CMOS multiple times.

Tried each RAM stick individually in all slots.

Flashed the latest BIOS using the Flash BIOS Button (LED blinked for ~4 mins, then board rebooted and led stayed solid both cpu ez debug and bios flash light).

With RAM installed → CPU LED stays on.

With RAM removed → DRAM LED lights up (so the CPU at least starts).

No bent pins, all power cables properly connected.

Still no POST or display.

2

No, that does not indicate that the CPU has started. With no DRAM, the system won’t even bother checking other components.

Sounds like a cooked CPU. Any chance of you trying it on a friend’s system, if they have AM4?

3

Most likely, the EPS12V CPU power rail is unstable. Inspect the processor pins for any burn marks or discoloration.
Also, smell and visually inspect the VRM area near the CPU socket — any burnt odor or darkened component indicates a possible MOSFET or VRM failure, which matches your symptoms.

4

Touch the cpu and see if it gets warm

5

No chance of trying it on another system

6

Theirs no burn marks or damage to any cpu pins or any cables , no smell either, anything i can try to narrow it down to psu? Its under warranty so i can rma it

7

Didn’t touch the cpu directly but I did touch the heat seak and yes it does get warm

8

I would suggest you check the CPU with some other board or vice versa. Try with some local vendors.

is this similar to your case?

10

any chance you can test out the CPU with a different stick of RAM other than the ones you own. It is not highly unlikely that all RAM sticks failed.

11

No,it stays power on but never post ,it stays on cpu debug light

12

Won’t that trigger the dram debug light on the mobo?

13

I thought you havent tried individual sticks. If it doesnt post even with one stick of RAM,
either all your RAM sticks are dead
or something is wrong with the CPU
It would be easier to check if the ram sticks are dead.

14

I tried all 4 sticks in all 4 slots, will still try to get a spare sticks and check

15

even if it boots with one single stick, the CPU should be good.

16

Are you using the connectors that came with the psu or after market/ modified wires to connect the psu to the gpu / mobo?

17

Yes,all cables being used are original,never used any modded cables even changed cpu and mobo cables with spare one brand new one

18

Is it possible to remove CMOS battery for 30mins or so, put it back and try to boot again with one RAM slide only ?

19

Tried, didn’t work

20

There is a chance that your SMPS is having issues ?

Is bitlocker enabled ?

21

Try OCCT PSU test once and reply.