Treat this as a diagnosis, not a shopping trip. 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

Treat this as a diagnosis, not a shopping trip. This usually comes down to heat, a bad BIOS setting or background load rather than a faulty B850 motherboard. 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.

Heat and airflow checks

Confirm the case has a clear front-to-back path and that no cable is resting against a 120mm or 140mm fan. Reseat the cooler and apply a fresh pea of paste if temps spiked after a recent strip-down.

Drivers, BIOS and Windows

Check that a recent Windows feature update did not swap your tuned driver for a generic Microsoft one overnight. Roll the GPU driver back to the last stable release, then do a clean reinstall using DDU so leftover files do not clash.

Test the memory profile

Run a short MemTest86 pass overnight to rule the 32GB kit in or out before blaming anything else. Run a short MemTest86 pass overnight to rule the 32GB kit in or out before blaming anything else.

FAQ

Is the B850 motherboard actually the problem?

Not until the software, heat, power and cable checks all pass. The B850 motherboard 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.

Does heat explain random crashes?

Often. A CPU sitting at 95C or a GPU hotspot past 100C will throttle or shut down to protect itself, so log temperatures across a full session rather than reading one quick number.

How do I know it is not the GPU driver?

Run DDU in safe mode and install one clean driver. If the symptom vanishes you found it; if it returns, move on to heat, power and memory checks.

Replace only what the evidence shows If the checks isolate the fault, compare current B850 motherboards on Evetech and upgrade the one part that proved unreliable.