Prime 95 and X2: What's the benefit of 2 instances?

[Markbnj]

I noticed that running Prime 95, single instance, it uses almost exactly 50% of each CPU core. So if the test is to see whether an overclocked CPU will produce incorrect results, the FPUs on both cores are being tested, and one instance should be good enough.

If the goal is to heat it up by using 100% of both cores, then running two copies will do it. So will running two copies of memtest, but obviously without using the FPUs. Is the reason for this to find out whether the CPU's behavior changes as it warms up? Are there overclocked CPUs that will run Prime95 correctly at 50% CPU utilization, but fail when the chip heats up at 100%?

Just wondering.

 

[Duvie]

I instance will not stress the cores enough.....YOu do want to test for max heat, max power and therefore max stress and this will only come from running 2 cores for at least 2 hours to 24 hours....When you do run 2 instances you should set affinity of each instance to a separate core (cpu 0 and cpu 1)

2 instances of memtest makes no sense cause there is only one memory controller and it sees all the cache when I run it...The dos version is the only one I recommend. the windows version I do not cause it cannot test the 200-300mb you likely have tied up just by booting up windows...therefore as a memory stick tester you are only testing 70% of your memory...


Yes on your last question....If you run affinity you will actually see that both cores are not created equal and you may have one core that can OC much higher but being held back by the other.....When I run 2.63ghz I would always fail with core 1 but core 0 would continue to run...This was at 1.5-1.52v.....

 

[Markbnj]

I noticed too that the type of test you choose affects how the program utilizes the core.

I haven't been able to get anything above 2530 mhz to stabilize and complete prime 95. Posted another thread on it. Be great if you could have a look and let me know if you have any ideas, seeing as we have the same chip.

http://forums.anandtech.com/messageview...atid=28&threadid=1709109&enterthread=y