cpu multiplier & SETI

[helloguy]

i read at setispy they said higher cpu multiplier,then u'll crunch seti slower....how come ??? anybody care2 explain ??

 

[JWMiddleton]

It is slower because it is less efficient, but this only applies to memory intensive applications. If your memory was running at the same speed as your CPU then there would be minimal delay in getting new data to crunch. But, in reality many of today's chips are running in the 10x to 20x range. The newest ones are better like the P4 Barton. You can take a chip running at 2 GHz and measure the difference at different multipliers. For example you can get 2GHz in the following ways:

16 x 133 MHz
12 x 166 MHz
10 x 200 MHz

The last one has a 200 MHz FSB giving you a 50% increase in memory access over the 133 MHz option. So, the CPU is waiting a much shorter time for new data and SETI is very memory intensive.

Hope that helps!

 

[helloguy]

oh....okie...basically it boils down to FSBxMultiplier.....icic thanks ~!~!~!

 

[MoFunk]

Yep, with seti you have to ignore the whole "clock speed thing". It's all about FSB. I was able to get my 1.4 overclocked to 2.35 but I was not able to get as high of a fsb as I wanted. So I am now at 2.1 but with a 215 FSB and 2:10 average WU's!!!!!

 

[Assimilator1]

Nice!:Q😀

 

[Wiz]

I have the same experience here, I got my AMD 1700+ running up around 2.35 but it's sweet spot for seti was hit by dropping the multiplier to 10X and setting the FSB sync at 220mhz. You've gotta have good ram for this stuff and an 8RDA+ really helps too 😉. Oh yeah, my timings are 3-2-2-2 😉

I'm seeing WU times in the 1:59 - 2:10 range on that box.

Contrast that with another system I have here, a AMD 2400+ running stock due to mobo constraints.
It's WU times are 2:44 - 3:05 each.
Still not shabby, but someday when I replace that mobo with a better one I will definitely see a nice improvement from that cpu.