Pc randomly freezing

My PC has been freezing repeatedly and I’ve been trying to isolate the cause. I can log into Windows and use the system for a short time before it either freezes or crashes. The freezes happen under load and sometimes even during simple tasks. At one point the PC started freezing even on the MSI MAG startup screen.

I checked the BIOS multiple times. XMP was originally on at 6000 MHz, but I disabled it. Freezing continued even with XMP off. I tested CPU Lite Load and tried different modes including 7 and 11, but the system still froze or crashed. I eventually reset the BIOS fully to defaults, which allowed the PC to boot normally again, but Cinebench still caused an instant crash with the fans ramping up heavily. This pointed toward a CPU or power-related instability rather than RAM.

I monitored temperatures in the BIOS hardware monitor and in Task Manager. Idle CPU temps were around 30°C, and the liquid cooler pump showed about 2700 RPM. I re attempted the cinebench tests and the CPU reached around 80°C but completed the test without crashing so I just gave up and I’m looking for help now.

At this point the system is stable only when idle or lightly loaded (I think now?) but any heavy CPU load causes crashes or freezes. (I also think) I’m trying to figure out whether the problem is the CPU, motherboard, PSU, or corrupted Windows installation or literally anything.

My pc specs

Intel Core i7-14700KF CPU, an NVIDIA GeForce RTX 4070 TI 16GB or RTX 5080 16GB GPU, 32GB of DDR5 RAM, and a 2TB PCIe 4.0 NVMe SSD.