BurnK7 is a single CPU stress test, not to mention it's not very stressful. If you want to run that on all CPUs you use the "&":
Code:
burnK7 & burnK7 & burnK7 & burnK7
(That will start up four of them.)
To stop it, the easiest way is probably to just kill the tasks:
It's a bit inconvenient but you can download
mprime and run that on a live CD, which is what I normally do. When starting it up in a terminal it gives you the same options as the Windows version. Select "Just stress testing", then pick one of the tests (e.g. blend test). That runs on all CPUs.
For your memtest, make sure you're using the latest version of memtest86
+.