Windows x64 better for Prime95 ?

Axel Fox · 2006-08-26, 15:54

Hi,

I'm currently running 2 instances of Prime95 on my new dualcore Pentium D 945. This CPU supports EM64T, but it is currently running a normal (32-bit) Windows XP Home. Would Prime95 benefit from me installing a 64-bit Windows XP ? And if so, how much more speed can I expect ?

Greets,
AxelFox.

Mystwalker · 2006-08-26, 16:28

Trial Factoring (TF) nearly doubles speed, LL and P-1 won't increase performance, as the code is still 32 bit (and much harder to port to 64 bit than the TF code).

Axel Fox · 2006-08-26, 17:30

Ah, I see.

So would it be better to set Prime95 to only Trial Factoring, or would it be better to keep letting PrimeNet decide what to assign ?

Greets,
AxelFox.

Prime95 · 2006-08-26, 18:47

TF doubles speed on an AMD64. I'm not sure what the difference is on a P4 architecture.

Don't bother upgrading. We need LL testers more than anything else and that will be the same speed whether you are running 32-bit or 64-bit prime95.

Dresdenboy · 2006-09-14, 09:09

TF speedup in 64 bit mode using version 24.11:
On P4 (actually a Xeon with Nocona core):
http://mersenneforum.org/showpost.ph...4&postcount=95

On K8:
http://mersenneforum.org/showpost.ph...5&postcount=21

During my quick search I didn't find any comparison of 32 bit vs. 64 bit TF on Core 2 Duo. It might also be a significant change as it is on K8, while the SSE2 code in 32 bit mode is also doing fine thanks to the higher throughput SSEn units.

Cruelty · 2006-09-14, 13:18

Quote:

Originally Posted by Dresdenboy

During my quick search I didn't find any comparison of 32 bit vs. 64 bit TF on Core 2 Duo.

http://www.mersenneforum.org/showpos...&postcount=236

2006-08-26, 15:54	#1
Axel Fox May 2003 2⁵×3 Posts	Windows x64 better for Prime95 ? Hi, I'm currently running 2 instances of Prime95 on my new dualcore Pentium D 945. This CPU supports EM64T, but it is currently running a normal (32-bit) Windows XP Home. Would Prime95 benefit from me installing a 64-bit Windows XP ? And if so, how much more speed can I expect ? Greets, AxelFox.

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2006-08-26, 16:28	#2
Mystwalker Jul 2004 Potsdam, Germany 3×277 Posts	Trial Factoring (TF) nearly doubles speed, LL and P-1 won't increase performance, as the code is still 32 bit (and much harder to port to 64 bit than the TF code).

2006-08-26, 17:30	#3
Axel Fox May 2003 96₁₀ Posts	Ah, I see. So would it be better to set Prime95 to only Trial Factoring, or would it be better to keep letting PrimeNet decide what to assign ? Greets, AxelFox.

2006-08-26, 18:47	#4
Prime95 P90 years forever! Aug 2002 Yeehaw, FL 7³×23 Posts	TF doubles speed on an AMD64. I'm not sure what the difference is on a P4 architecture. Don't bother upgrading. We need LL testers more than anything else and that will be the same speed whether you are running 32-bit or 64-bit prime95.

2006-09-14, 09:09	#5
Dresdenboy Apr 2003 Berlin, Germany 19² Posts	TF speedup in 64 bit mode using version 24.11: On P4 (actually a Xeon with Nocona core): http://mersenneforum.org/showpost.ph...4&postcount=95 On K8: http://mersenneforum.org/showpost.ph...5&postcount=21 During my quick search I didn't find any comparison of 32 bit vs. 64 bit TF on Core 2 Duo. It might also be a significant change as it is on K8, while the SSE2 code in 32 bit mode is also doing fine thanks to the higher throughput SSEn units.