Windows 32bit vs 64bit mfaktc/cudalucas

[bcp19]

My GPU machine runs the 32 bit version of Vista and I was wondering if anyone has done testing to see if there is a marked difference in using the 64 bit version over the 32 bit version. My 64 bit machine has a quad core (which someone said is actually 2 dual cores) and I'd have to swap out power supplies as well as cards (which also means I'd also have to remove the CPU heat sink to get the PS out), so I was thinking that upgrading to a 64 bit OS would be the easier way to go, provided it would be a benefit to the programs running. Thanks.

[Dubslow]

In mfaktc I know there is a not insignificant difference (try looking at the PDF in the FAQ thread). I don't know about CUDALucas.

[TheJudger]

Try to look at the README.txt for mfaktc:

A 64bit built is prefered except for some old lowend GPUs because the
performance critical CPU code runs ~33% faster compared to 32bit. (measured
on a Intel Core i7)

Oliver

[kladner]

critical CPU code runs ~33% faster compared to 32bit. (measured on a Intel Core i7)

That is roughly true on a Phenom II, as well: Win7-64 vs. XP-32.

[Christenson]

I would expect little effect when running CUDAlucas..as it's CPU component is very, very small. Now on mfaktc, we are always handling 64 bit or larger operands, and there can be scads (more than 32 bits worth) of them, so 64 bits will be faster.

[bcp19]

Thanks for all the input, I went ahead and ordered a 64 bit version so should have in within a week.

[bcp19]

Just an update, I installed the 64 bit version of Vista last night and what I am seeing so far is pretty impressive:

P95 running 45M LL went from .065 to .048 sec per iteration.
CUDALucas went from .0168 to .0115 sec per iteration.
Mfaktc went from 65M/s to 100M/s

[kladner]

Originally Posted by bcp19

Just an update, I installed the 64 bit version of Vista last night...

Purely out of curiosity, why did you go with Vista and not Windows 7?

[bcp19]

Originally Posted by kladner

Purely out of curiosity, why did you go with Vista and not Windows 7?

1) cost
2) on the MS website it said 32 bit Vista to 64 Win7 = new install where 32 to 64 Vista = upgrade
3) I have 3 Vista machines and 1 Win7 and I dislike the changes

[kladner]

Originally Posted by bcp19

1) cost
2) on the MS website it said 32 bit Vista to 64 Win7 = new install where 32 to 64 Vista = upgrade
3) I have 3 Vista machines and 1 Win7 and I dislike the changes

I fully understand. I skipped over Vista, and wanted to keep the XP license intact. So for me a new install version was a good fit.

As to change, there are aspects of 7 that are OK once you adjust to them. But there are others which irritate me, with my XP habits.

[bcp19]

Originally Posted by kladner

I fully understand. I skipped over Vista, and wanted to keep the XP license intact. So for me a new install version was a good fit.

As to change, there are aspects of 7 that are OK once you adjust to them. But there are others which irritate me, with my XP habits.

I know, the one thing I hate MOST is the constant "You need to have permission to run that" and it freezes the whole system while a stupid pop-up prompts you to continue. I used to get the pop-up everytime I ran P95 or GPU-Z. Frustrating.