Prime95 v27.7 build 2's Blend test has 82 FFTs. However, even using the older version of Prime95 that has 70 FFTs (I don't know which version that is), it will take longer than 17.5 hours to go through all 70 FFTs at 15 minutes per FFT because there is a delay in between each FFT. This means the math is not simply 70x15 equals 1,050, 1,050 divided by 60 equals 17.5.
For example, in order to find out how many FFTs Prime95 v27.7 build 2 has in its Blend test, I ran the Custom Blend test at 1 minute per FFT and waited until I saw it starting up the first FFT a 2nd time. It took exactly 105 minutes to get through all 82 FFTs instead of 82 minutes. I expected 82 minutes, but 105 minutes is what it took. Now, 82x15 equals 1,230 minutes. 1,230 minutes divided by 60 is 20.5, which means 20.5 hours if there's no delay in between each FFT. However, there happens to be a delay in between each FFT. So how long would 82 FFTs actually take at 15 minutes per FFT? I am guessing it would take approximately 24 hours and 49 minutes if the delay is always the same in between each FFT test.
Here's why I think that: 82 divided by 105 is about 0.79. This means that there's a 21% increase over my expected 82 minutes. So 20.5 hours multiplied by .21 for 21% equals 24.805 hours which means 24 hours, 48 minutes, and 18 seconds.
If it's always a 21% increase above the expected (that is, the expected as found by multiplying the number of FFTs by the number of minutes for each FFT and then dividing by 60), then 10 minutes per FFT for 82 FFTs would be 16 hours, 32 minutes, and 27 seconds. I mean, 13.67 x .21, then add the result to 13.67.
I doubt that it's always a 21% increase, but this is all I have to go by right now.
Edit: Prime95 v27.7 build 2 is the only version right now that supports the AVX instruction set. However, Windows 7 SP1 is required because SP1 provides access to the AVX instruction set. Or, it provides support - or however it should be described.
I'll guess I'll just try feeling it out then. What is the absolute worst that could happen if the overclock isn't stable though? I completely corrupt my game and have to reinstall, damage to data on my ssd/hdd? Or just random crashes, that sort of thing?