Maximum memory usage of Prime?

[cl55amg]

Hi guys, hope you help me.

I'm wondering If Prime is really restricted to a maximum of 1.6GB memory Usage, cause on my system Prime can't adress more.

Here is the test environment:
Win XP 32 Bit with 4GB RAM and Dual Core CPU.

/3GB Switch is active, so Windows 32Bit recognizes 2.93GB RAM.
But don't matter how many Prime instances are running, Prime can only adress 1.6GB. (Tested with different Prime versions).

Is the adressing amount of 1.6GB a general limitation of Prime?

Thank you

[davieddy]

If my understanding is right, a 2048K FFT stores this number
of elements in floating point (8 bytes per element). This gives an
estimate of 16MB for the requirement. Sounds as if 1.6GB is
well surplus to what is needed.

[S485122]

Only during stage 2 of P-1 factoring will prime95 use a lot of memory. But if you use a 32 bits OS and thus the 32 bits version of Prime95 you are indeed limited to 1,6 GB. If you use the 64 bit version of Prime95 (under a 64 bit OS of course) the limit disapears : I have one machine where Prime95 uses 3,6 GB memory.

[cl55amg]

Originally Posted by S485122

Only during stage 2 of P-1 factoring will prime95 use a lot of memory. But if you use a 32 bits OS and thus the 32 bits version of Prime95 you are indeed limited to 1,6 GB. If you use the 64 bit version of Prime95 (under a 64 bit OS of course) the limit disapears : I have one machine where Prime95 uses 3,6 GB memory.

Thanks!

Would you please tell me wich Prime version and OS you are using? Does your machine run Vista 64Bit oder XP 64Bit?

[Cruelty]

Originally Posted by cl55amg

Vista 64Bit oder XP 64Bit?

zee Germans?
S485122 is probably using this one.

[S485122]

Originally Posted by cl55amg

Would you please tell me wich Prime version and OS you are using? Does your machine run Vista 64Bit oder XP 64Bit?

I indeed run Prime95 from the p64v2414.zip file on Windows XP pro 64.
Jacob

[ATH]

Originally Posted by S485122

Only during stage 2 of P-1 factoring will prime95 use a lot of memory. But if you use a 32 bits OS and thus the 32 bits version of Prime95 you are indeed limited to 1,6 GB. If you use the 64 bit version of Prime95 (under a 64 bit OS of course) the limit disapears : I have one machine where Prime95 uses 3,6 GB memory.

Can you run a 64 bit OS without a 64 bit processor?

[kuratkull]

Originally Posted by ATH

Can you run a 64 bit OS without a 64 bit processor?

No, but 64bit OS's usually have backwards compability.

[ATH]

So with a 32 bit processor you are stuck to max 3Gb Ram? and max 1.6Gb for 1 program?