Originally Posted by MooMoo
One noobish question about Prime95, what are these FFTs? Whats the difference of small FFT and large FFT?
Small FFTs are literally that, small tests where all of the data fits on the L2 cache of the CPU itself. RAM isn't tested much at all, but they do put a great deal of stress on the Floating Point Unit and do generate significant heat. The FFT lengths for the "Small" is between 8K and 16K.
In-place large FFTs generate even more heat and consume a great deal of power and they test your RAM to some extent. The In-place large FFTs are between 128K and 1024K in size. They test 8 MB of memory.
The Blend test tests a bit of everything, and places even more stress on your RAM. For an i5, the FFTs range in size between 8K and 4096K (4M) The default is to test 1600 MB of memory.
You can then customize the tests and change the minimum and maximum FFT lengths, the time to run each FFT size, the amount of memory to use, and whether or not to test the FFTs in-place.
For this club, we all use the Blend test.
Some of us use the Custom test (with all Blend default settings) and we change the Memory to use to an amount that puts our Physical Memory Used percentage greater than or equal to 90% (which becomes a "super stable" instead of "stable" club submission).