Note exactly what changed before the fault appeared. Below is an ordered, South African gaming checklist for the symptom in the heading, written so each step is something you can verify yourself before booking a repair or buying a replacement.
Quick Answer
Note exactly what changed before the fault appeared. This usually comes down to drivers, a hot NVMe drive or background load rather than a faulty Core Ultra 9 285K. Run a fixed 20-minute test after each change and keep the one that holds at a steady frame rate or a stable temperature under 85C.
Driver and BIOS hygiene
Roll the GPU driver back to the last stable release, then do a clean reinstall using DDU so leftover files do not clash. Roll the GPU driver back to the last stable release, then do a clean reinstall using DDU so leftover files do not clash.
Storage and SSD checks
Check SMART data for a failing 1TB or 2TB SSD that is silently retrying reads. Check SMART data for a failing 1TB or 2TB SSD that is silently retrying reads.
RAM and EXPO checks
Drop to two sticks in the correct A2 and B2 slots if four-DIMM configs refuse to post cleanly. Drop to two sticks in the correct A2 and B2 slots if four-DIMM configs refuse to post cleanly.
FAQ
Is the Core Ultra 9 285K actually the problem?
Not until the software, heat, power and cable checks all pass. The Core Ultra 9 285K is the platform under review, so rule out the cheaper causes first and only suspect the hardware once a clean reinstall and a default-BIOS test still fail.
Is it safe to keep using the PC like this?
If it shuts down or blue-screens, stop heavy loads until you find the cause. Repeated hard crashes can corrupt the boot drive, so back up your data before deep testing.
How long should each test run?
Use a fixed 20-minute load that reliably triggers the fault. A shorter burst can hide a thermal or memory problem that only appears once the system is fully warmed up at 80C or higher.
Pro Tip
one variable per test: adjust a setting, re-run the same 20-minute load, then decide.