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Old 2009-08-26, 20:21   #1
storm5510
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Default Why Not Prime95

Why can't Prime95 be used to do this work?

I can't run Factor5 on my primary computer. It slows it down to a crawl. I have it running on my old P4 computer.

:surprised
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Old 2009-08-26, 20:46   #2
Mini-Geek
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Quote:
Originally Posted by storm5510 View Post
Why can't Prime95 be used to do this work?
See for yourself:
Quote:
[Main thread Aug 26 15:34] Mersenne number primality test program version 25.11
[Main thread Aug 26 15:34] Error: Worktodo.txt file contained bad factoring assignment: -973039125
[Main thread Aug 26 15:34] Illegal line in worktodo.txt file: Factor=3321928171,60,70
Prime95 only supports exponents up to a certain size, and that size is below that needed to make billion digit Mersennes. I'm not sure if the problem is superficial (e.g. the worktodo parser uses a signed 32-bit int which maxes out at about 2B, while these candidates are about 3.3B) or real (e.g. Prime95 lacks the ability to do numbers that large), but either way it exists.
Quote:
Originally Posted by storm5510 View Post
I can't run Factor5 on my primary computer. It slows it down to a crawl. I have it running on my old P4 computer.

:surprised
It would most likely make a huge difference to Factor5's performance impact on your computer to change its priority to something below any app you'd be running. To do this, (assuming Windows)
open Task Manager, go to Processes, right click on factor5.exe, and choose Set Priority > Low. That will be remembered until you stop/start the process, then you'll have to do it again. (not sure if that is acceptable)
or
For a command-line/shortcut alternative, use 'start /low' before the line. (use 'start /?' to see all options, you might want to set some others) This will, of course, take effect every time, and will begin when you restart the factor5 process using this line.

Last fiddled with by Mini-Geek on 2009-08-26 at 20:50
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Old 2009-08-26, 23:09   #3
storm5510
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I think you covered everything. I knew about the priority in the task manager, but only looked at it one time before. Out of sight, out of mind.

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