2012 iMac kernel panicking for no apparent reason

[TechInit]

Hi all, hope you're well!

I've had my 2012 iMac for a small while now, and I've really been enjoying it, however, I've experienced a lot of kernel panicking for no apparent reason.

I've rigorously stressed both the CPU and GPU with Cinebench and Heaven running at the same time (with bad thermals mind you as I'm waiting for my new hard drive before I clean it out), and it showed no signs of slowing up. The thermals are pretty bad, both reaching about 100 degrees as I haven't cleaned it out yet.

I do have a dead hard drive in here, which I think could be causing the problem. I'm currently using the 128GB SSD from the fusion drive, and waiting for a 4TB Hard Drive to arrive before I do any cleaning. Could this be the issue? Could the dead hard drive being in there still be an issue?

I've also heard that it could be Catalina causing the issue, and I'm currently trying to downgrade to Mojave to test this theory out. Other than that, I'm pretty much out of ideas.

My list of theories are:
-Thermals
-Hardware (CPU and GPU)
-Dead RAM DIMM
-Dead Hard Drive
-Catalina
-The fusion drive splitting gone wrong?

I've heard that the first 12 lines of the kernel panic are the most important, so here they are:
panic(cpu 0 caller 0xffffff802c612667): "AppleAHCIDiskQueueManager::setPowerState(0xffffff8068f60b40 : 0xffffff7faefb05d2, 3 -> 2) timed out after 100467 ms"@/AppleInternal/BuildRoot/Library/Caches/com.apple.xbs/Sources/xnu/xnu-6153.141.2.2/iokit/Kernel/IOServicePM.cpp:5296
Backtrace (CPU 0), Frame : Return Address
0xffffffa3dc523b40 : 0xffffff802bf1868d
0xffffffa3dc523b90 : 0xffffff802c052ab5
0xffffffa3dc523bd0 : 0xffffff802c04463e
0xffffffa3dc523c20 : 0xffffff802bebea40
0xffffffa3dc523c40 : 0xffffff802bf17d57
0xffffffa3dc523d40 : 0xffffff802bf18147
0xffffffa3dc523d90 : 0xffffff802c6bf2bc
0xffffffa3dc523e00 : 0xffffff802c612667
0xffffffa3dc523e50 : 0xffffff802c611f49
0xffffffa3dc523e60 : 0xffffff802c6294de
0xffffffa3dc523ea0 : 0xffffff802c610cf8
0xffffffa3dc523ec0 : 0xffffff802bf5a645
0xffffffa3dc523f40 : 0xffffff802bf5a171
0xffffffa3dc523fa0 : 0xffffff802bebe13e

Idk if it matters, but here are the specifications:
-Core i7 3770
-GTX 680MX
-128GB SSD (split from fusion drive)
-32GB RAM

 

[TechInit]

Catalina turns out to be the issue! I've downgraded to Mojave and things seem to be okay.

I'd recommend if anyone is experiencing random but persistent kernel panics (I seemed to be okay for the 45 minutes to 1 hour, and then after the first they happened every 10-13 minutes) to try downgrading to Mojave