Maximize chances of finding Mersenne Prime

[dennisonprime]

Hello All, I am new here. Just set up prime95 on a high end PC. What settings should I use to maximize my chances of finding a Mersenne Prime?

[VBCurtis]

If you're trying to eek every last percentage point of performance, telling us "high end" isn't helpful. What CPU? Overclocked? Memory speed? Dual channel or 4?

Fast CPUs can saturate the memory bus running Prime95, so memory speed is paramount. If you run stock DDR3-1600, even a midrange i5 will be memory-limited. There's plenty of threads around about running the benchmark to identify how many threads you should give each test, but if you list your cpu/memory specs someone will likely save you the trouble.

[Siegmund]

There are two sides to a question like this, and we don't know which one you're asking about:

For your work assignments, you want first-time tests, on numbers as small as possible. Double-checks are much less likely to find new primes, and the other work types (P-1, ECM, trial factoring) never find new primes.

Maximizing the performance of your system can have many facets, depending how crazy you are about messing with your hardware. But a simple first step is to run the Benchmark test (on the Options menu), and see if you get better performance from applying 4 threads to the same exponent, or 1 thread each to 4 different exponents.

[MattcAnderson]

Hi,
Welcome to our mersenneforum!!! I wish you much success.

As a warning, it is important to consider who owns the computer that will run the Prime95 software. If it is a work computer, please make sure you have permission to do the extra work. Running the processor hot draws many watts of electricity and it matters who is paying the electric power bill.

But if these things are not an issue, I suggest following the menus, and let the Prime95 software do what it wants to do, and you will help this project.

Again welcome.

Regards,
Matt

[dennisonprime]

Dear All,

Thanks for the feedback. In summary, I want to locate the next Mersenne Prime (and claim the prize) as quickly as possible. I have this computer (yes with the freedom to run the software).

Specs below:
E5-2690 v2 @3GHz (8 processors)

It runs 10 workers. What Type of work to get can I assign it to maximize the chances of locating a Mersenne Prime in the shortest time possible?

[axn]

Originally Posted by dennisonprime

What Type of work to get can I assign it to maximize the chances of locating a Mersenne Prime in the shortest time possible?

You'll want "first time LL test", as that is the one with mathematically the highest probability of finding a prime. Even here, the tests span a large range (from Cat 1 smallest to Cat 4 largest), and you need Cat 1. But for that: a) you need to opt in (http://www.mersenne.org/thresholds/ ), and b) prove that your computer is a reliable, high-thruput cruncher (which will take some time to establish).

Additionally, running 10 workers per CPU might not be most optimal configuration for you. Because of its large cache, 1 worker with 10 threads might give a better thruput. Even if it is actually worse (by 1 or 2%), the latter configuration will get you the required history much quicker, and so you'll be crunching Cat 1 tests that much sooner.

[dennisonprime]

Thanks axn, but in this case, what settings should I choose in the prime95 software? No of workers: 1,Type of work: First time tests?

I am unable to relate the options to the different types of options on the mersenne/maths page.

[axn]

Originally Posted by dennisonprime

No of workers: 1,Type of work: First time tests?

Correct. This is assuming you're running single socket. If you have more than one socket, then put that many as No of workers.

Also, CPUs to use (multithreading) = 10.

And you need to opt in for smallest exponents @ http://www.mersenne.org/thresholds/