- Prime 95 v26: no AVX testing. Good stress test for primarily CPU. You can load up your RAM too though. I'd only stress one or the other if you're trying to rule one in/out as an issue.
- Later versions of prime 95 use AVX loads. Still a valid test. It'll just heat things up a little more, but if you're not OC'd then no biggie anyway.
- Asus ROG Realbench is a good all around stress test that hits CPU and GPU simultaneously, + incremental RAM selections. Does use some mild AVX loads also so its a great all around. If you run this for 8 hours and it all tests good, you're typically in great shape, unless there's a RAM issue which this will miss sometimes.
- For RAM only, good old memtest (passmark.com). Create a bootable USB...