Quote:
Originally Posted by nuutti
How much faster GMPECM 5 is in p1 factoring in the stage 2?
I am currently running P1 for:
Pminus1=67108864,4000000,5000000,0,0
Can I use GMPECM 5 for runnig stage 2 in my test ?
(I have 2 Gbytes of memoy)

For a number this large Prime95 is faster. Gmpecm can test to higher bounds than Prime95, for 2^671088641 this is probably not a consideration, but I have done some timings on the smaller fermat numbers and I estimate that a P4 2.66GHz could test 2^2621441 to B1=4290M in about 28 days with Prime95, or 2^5242881 in about 60 days. From that point the fastest way to either extend stage 1 or start stage 2 is to use gmpecm separately on F18, F17, F16, etc.
According to
http://www.mersenne.org/ecmf.htm, F18, F17, F16, F15 have only been tested to B1=32M, 64M, 250M, 1000M respectively.