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Q Code 42, red CPU light. PC will not post.

Level 7
ASUS ROG Crosshair X670E Hero, AM5 Ryzen 7900x, Trident Z5 32GB (2 x 16GB) DDR5 6400, AMD 7900XTX, Kingston FURY 2TB M.2 (X2 in RAID 0), temporary Cooler Master Hyper 212 CPU cooler (this could be important)

I built this PC yesterday and it was working mostly fine until hard crashing 2 minutes after soft crashing-to-desktop while playing Modern Warfare. PC getting stuck on the code 42 with a red CPU light.

Here are the order of all important events.

1. Flashed BIOS to 0805 before initial BIOS setup or windows install (latest version as of 1/29/23) Everything goes smooth.
2. Install Windows 11 on dual Kingston Fury's in RAID 0. Install goes smooth.
3. Install all Windows updates, drivers, chipset, graphics, everything. Smooth.
4. Set RAM to stock 6400MHz by setting DOCP 1 in BIOS. Smooth. PC posts no problem and I'm back in Windows.
5. I start testing out some games and right away run into a CPU overheating issue on Battlefield 2042 and Modern Warfare. CPU would reach up to 100C and the game would crash (AMD states 95C is normal for these CPUs). Destiny 2 however ran great at 180fps 5k ultrawide resolution. 2/10 of these crashes were hard crashes, including the final crash where I got stuck at the 42 code. The other 8 crashes I remained in windows and the PC ran fine. I'm using a temporary Cooler Master Hyper 212 CPU cooler because the Kraken 360mm AIO was delayed for shipment. Maybe this caused the problem? Multiple people are talking about similar Q 42 issues on Reddit.
6. I started trouble shooting the CPU overheating issue and implemented three changes.
a.) Set Precision boost in the BIOS to level 1 (capping CPU at 90C)
b.) Removed thermal paste. Turned out the Arctic MX-4 I used was expired. It looked fine (not watery or solid), but applied new paste just to be safe.
c.) capped frame rates in Battlefield and MW2
7. Games were more stable, but the CPU spiked once near 100C and crashed.
8. Set Precision boost to level 2, capping the 7900X to 80C
9. Ran a CPU stress test and it stayed perfectly at 80C, not going a degree above.
10. Tried MW2 again, and this time it was the most stable. The CPU sat between 75-88, well below the 95C normal operating temp. I played for the longest I had so far, but ended up crashing out of the game with error code 0x00001338 (11571)N. Like most previous crashes, I remained in windows. I was even searching for the error code on google for a couple minutes. While reading a post where a Reddit user said the error code was memory issue related, the PC shut off out of nowhere. No BSOD, just shut down ~2 minutes after crashing out of the game.
10. Boot back up and I'm stuck with the 42 code, and a red CPU light. I didn't know it yet, but this was going to become a major FML moment.
11. Try just about everything everyone has recommended for code 42, minus replacing hardware (yet).
a.) Clear CMOS, remove CMOS battery
b.) Check all connections
c.) 1 stick of ram, swapped
d.) Reinstall CPU & GPU
e.) Reinstall 0805 BIOS, then flashed to previous 1705 version

My 2 leading ideas is either the CPU was damaged, or the board is bad. What confuses me about the CPU getting damaged from hitting 100C 8-10x, is after I throttled down to 80C with precision boost, it was working fine for an hour with CPU temps between 75-88C. The PC crashed/shut down 2 minutes after the game crashed, and the CPU temps were under 90C when the game crashed. But the 42 code is complemented by a lovely red CPU light.

I have a new CPU on order, arriving tomorrow. If that doesn't work I'm trying a new motherboard.

And that's where I'm at.

Does anyone have input on what I should try next?


Level 7

I replaced the 7900x CPU with a 7700x. I guess it was a bad 7900x? Seems like that would be a very rare, but the 7900x was regularly spiking to 100c under load, which is not supposed to happen. Even with precision boost enabled to 90c it was still spiking to 100+, so something was wrong. I researched cooling the 7000 series, and even your most basic $30 cooler works fine with the 7950x, the CPU will just throttle when temps hit 95c, so it wasn't my cooler. Chalking this up to a bad CPU, as rare as that must be. The new 7700x is working perfectly. Temps spike to 95, as it's supposed to, but the CPU immediately throttles itself. I have not seen temps go beyond 96.