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Old 2005-07-11, 01:03   #1
Carlos
 
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Jan 2005

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Question Importance of fast ram

How inportant is it to have fast ram for LL testing? In other words, how often does mprime access main ram as verses cache during LL testing? Would it make any noticeable difference if ram was set at 133 mhz verses 166mhz?

Carlos
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Old 2005-07-11, 05:40   #2
E_tron
 
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Sep 2002
Austin, TX

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ram isn't THAT important, so don't panic if your not running the fastest ram. The processor is what really counts.

I wish i still had the numbers, but I ran my Athlon XP machine on DDR200 memory for the first 3 days of its existence(1.6Gb/sec). Then i upgraded to dual channel DDR400(6.4Gb/sec).

I saw maybe a 10% boost by quadrupling my memory bandwidth.
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Old 2005-07-26, 13:06   #3
kaeptn_kork
 
Sep 2002

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some benches of my machine:

CPU: A64 Venice - 2520 MHz
RAM: Dualchannel, Timings 2-2-2-8

RAM @ 140 MHz
AMD Athlon(tm) 64 Processor 3000+
CPU speed: 2520.17 MHz
CPU features: RDTSC, CMOV, Prefetch, 3DNow!, MMX, SSE, SSE2
L1 cache size: 64 KB
L2 cache size: 512 KB
L1 cache line size: 64 bytes
L2 cache line size: 64 bytes
L1 TLBS: 32
L2 TLBS: 512
Prime95 32-bit version 24.13, RdtscTiming=1
Best time for 512K FFT length: 18.689 ms.
Best time for 640K FFT length: 24.403 ms.
Best time for 768K FFT length: 29.674 ms.
Best time for 896K FFT length: 35.577 ms.
Best time for 1024K FFT length: 39.395 ms.
Best time for 1280K FFT length: 50.069 ms.
Best time for 1536K FFT length: 61.246 ms.
Best time for 1792K FFT length: 74.247 ms.
Best time for 2048K FFT length: 82.744 ms.
Best time for 2560K FFT length: 111.362 ms.
Best time for 3072K FFT length: 135.982 ms.
Best time for 3584K FFT length: 164.057 ms.
Best time for 4096K FFT length: 183.018 ms.
Best time for 58 bit trial factors: 4.740 ms.
Best time for 59 bit trial factors: 4.742 ms.
Best time for 60 bit trial factors: 4.719 ms.
Best time for 61 bit trial factors: 4.742 ms.
Best time for 62 bit trial factors: 8.489 ms.
Best time for 63 bit trial factors: 8.497 ms.
Best time for 64 bit trial factors: 11.028 ms.
Best time for 65 bit trial factors: 10.932 ms.
Best time for 66 bit trial factors: 10.938 ms.
Best time for 67 bit trial factors: 10.928 ms.


RAM @ 180 MHz
AMD Athlon(tm) 64 Processor 3000+
CPU speed: 2520.14 MHz
CPU features: RDTSC, CMOV, Prefetch, 3DNow!, MMX, SSE, SSE2
L1 cache size: 64 KB
L2 cache size: 512 KB
L1 cache line size: 64 bytes
L2 cache line size: 64 bytes
L1 TLBS: 32
L2 TLBS: 512
Prime95 32-bit version 24.13, RdtscTiming=1
Best time for 512K FFT length: 18.531 ms.
Best time for 640K FFT length: 24.235 ms.
Best time for 768K FFT length: 29.398 ms.
Best time for 896K FFT length: 35.262 ms.
Best time for 1024K FFT length: 39.085 ms.
Best time for 1280K FFT length: 49.716 ms.
Best time for 1536K FFT length: 60.845 ms.
Best time for 1792K FFT length: 73.793 ms.
Best time for 2048K FFT length: 82.182 ms.
Best time for 2560K FFT length: 109.970 ms.
Best time for 3072K FFT length: 133.706 ms.
Best time for 3584K FFT length: 161.483 ms.
Best time for 4096K FFT length: 180.008 ms.
Best time for 58 bit trial factors: 4.733 ms.
Best time for 59 bit trial factors: 4.738 ms.
Best time for 60 bit trial factors: 4.726 ms.
Best time for 61 bit trial factors: 4.739 ms.
Best time for 62 bit trial factors: 8.516 ms.
Best time for 63 bit trial factors: 8.500 ms.
Best time for 64 bit trial factors: 11.010 ms.
Best time for 65 bit trial factors: 10.940 ms.
Best time for 66 bit trial factors: 10.975 ms.
Best time for 67 bit trial factors: 10.901 ms.


RAM @ 229 MHz
AMD Athlon(tm) 64 Processor 3000+
CPU speed: 2520.02 MHz
CPU features: RDTSC, CMOV, Prefetch, 3DNow!, MMX, SSE, SSE2
L1 cache size: 64 KB
L2 cache size: 512 KB
L1 cache line size: 64 bytes
L2 cache line size: 64 bytes
L1 TLBS: 32
L2 TLBS: 512
Prime95 32-bit version 24.13, RdtscTiming=1
Best time for 512K FFT length: 18.446 ms.
Best time for 640K FFT length: 24.122 ms.
Best time for 768K FFT length: 29.257 ms.
Best time for 896K FFT length: 35.120 ms.
Best time for 1024K FFT length: 38.930 ms.
Best time for 1280K FFT length: 49.512 ms.
Best time for 1536K FFT length: 60.623 ms.
Best time for 1792K FFT length: 73.466 ms.
Best time for 2048K FFT length: 81.824 ms.
Best time for 2560K FFT length: 108.472 ms.
Best time for 3072K FFT length: 132.590 ms.
Best time for 3584K FFT length: 159.881 ms.
Best time for 4096K FFT length: 178.367 ms.
Best time for 58 bit trial factors: 4.724 ms.
Best time for 59 bit trial factors: 4.741 ms.
Best time for 60 bit trial factors: 4.724 ms.
Best time for 61 bit trial factors: 4.748 ms.
Best time for 62 bit trial factors: 8.519 ms.
Best time for 63 bit trial factors: 8.506 ms.
Best time for 64 bit trial factors: 11.013 ms.
Best time for 65 bit trial factors: 10.939 ms.
Best time for 66 bit trial factors: 10.950 ms.
Best time for 67 bit trial factors: 10.907 ms.


as you can see, not much of a difference here

Last fiddled with by kaeptn_kork on 2005-07-26 at 13:07
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Old 2005-07-26, 14:25   #4
Dresdenboy
 
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Apr 2003
Berlin, Germany

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Quote:
Originally Posted by kaeptn_kork
as you can see, not much of a difference here
The more recent versions of Prime95 make better use of the processor caches and are less dependend on memory speeds. The difference will be more significant when using older versions (IIRC <=24.6).
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Old 2005-07-27, 00:11   #5
Carlos
 
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Jan 2005

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Thanks for the great information.

Carlos

Last fiddled with by Carlos on 2005-07-27 at 00:12
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