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Old 2009-06-23, 17:31   #1
Primeinator
 
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"Kyle"
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Default Best Unit for the Job?

Changing my mind from a previous thread, I am just going to save up and buy a more powerful crunching unit instead of just a new CPU. So...my question is this. Without being prohibitively expensive, and just looking for a computer that will be used mainly for number-crunching, what is the best combination of CPU, RAM, Motherboard, etc for performing large LL tests 45M plus and eventually going for the hundred million digit challenge? Also, are there any CPUs coming out in the next year or two that are going to be breakthroughs so to speak on LL speed, etc? Thanks.

Also, what sites are the best for custom building such a machine?
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Old 2009-06-23, 17:39   #2
henryzz
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Originally Posted by Primeinator View Post
Also, what sites are the best for custom building such a machine?
you home is the best site
it is often possible to save quite a bit of money

I would probably recommend an i7 920 currently for good bang per buck for one pc.
If you are willing to pay the electricity for several pcs i think it is possible to get 2-3 Core 2 Quads for the same money.
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Old 2009-06-24, 08:54   #3
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eventually going for the hundred million digit challenge? Also, are there any CPUs coming out in the next year or two that are going to be breakthroughs so to speak on LL speed, etc? Thanks.
I suspect by the time we are seriously shooting for the 100 million digits prize, anything you could buy today, or even this year, will be completely out of date, probably consigned to test factoring.
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Old 2009-06-24, 10:20   #4
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I suspect by the time we are seriously shooting for the 100 million digits prize, anything you could buy today, or even this year, will be completely out of date, probably consigned to test factoring.
I don't think so. With a Core i7 920 (nice overclockable to 3,7 Ghz) and 8 hyperthreads you can decrease your time for a 100M number to around 3-7 years ...

Last fiddled with by joblack on 2009-06-24 at 10:20
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Old 2009-06-24, 11:48   #5
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I don't think so. With a Core i7 920 (nice overclockable to 3,7 Ghz) and 8 hyperthreads you can decrease your time for a 100M number to around 3-7 years ...
OK, consider the machines that take 3-7 years to do today's exponents. (33-45 million bits) What would you recommend people do with them today? Do you think those machines had any reasonable chance of finding the first 10 million digit prime? Seems pretty slim odds to me.
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Old 2009-06-24, 14:23   #6
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OK, consider the machines that take 3-7 years to do today's exponents. (33-45 million bits) What would you recommend people do with them today? Do you think those machines had any reasonable chance of finding the first 10 million digit prime? Seems pretty slim odds to me.
You mean the first 100M digits prime? Perhaps its only 2 years (it's hard to estimate the time of the Core i7 if you don't have one) - the chance to find a 10M prime numbers isn't that much higher.

Anyway with a Core i7 I would definitely go for a 100M number (as I started some weeks ago -> you need to make regular backups including a RAID1). If the machine is outdated you can update it to a higher one (then you can still use this one for office work and smaller exponents). With Murphy's Law you'll double processing power every 2 years so you could upgrade then ...

The important step is to start calculating and perhaps upgrade to a higher cpu in the future ...

Last fiddled with by joblack on 2009-06-24 at 14:27
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Old 2009-06-24, 14:54   #7
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...With Murphy's Law you'll double processing power every 2 years so you could upgrade then ...
I think Murphy's Law is something else.
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Old 2009-06-24, 15:00   #8
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I think Murphy's Law is something else.
LMAO my fault - of course I mean Moore's Law ;).
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Old 2009-06-24, 15:20   #9
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I think Murphy's Law does apply here. It states that the box will be blown by lightning at 99% of a 100M digit test. (Could actually be more likely than the result being prime.)
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Old 2009-06-24, 16:16   #10
Primeinator
 
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I think Murphy's Law does apply here. It states that the box will be blown by lightning at 99% of a 100M digit test. (Could actually be more likely than the result being prime.)
Which is why he said to make back ups and preferably store them on a USB drive or other device

Interesting though. I found this system, which seems to be a very good price. What do you guys think, would it be good for quickly completing large LLs 45M +? I know it is not an i7...but it is still a fast quad core.
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Old 2009-06-24, 17:05   #11
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Originally Posted by Primeinator View Post
Changing my mind from a previous thread, I am just going to save up and buy a more powerful crunching unit instead of just a new CPU. So...my question is this. Without being prohibitively expensive, and just looking for a computer that will be used mainly for number-crunching, what is the best combination of CPU, RAM, Motherboard, etc for performing large LL tests 45M plus and eventually going for the hundred million digit challenge? Also, are there any CPUs coming out in the next year or two that are going to be breakthroughs so to speak on LL speed, etc? Thanks.

Also, what sites are the best for custom building such a machine?
Hmm break this down into 2 parts::

1) Components - intel core i7/nehalem (the 920 is nice so are some of the more expensive parts which should drop again in price this fall)
6 gigs of ddr3 dram - preferrably a high speed/low (CAS) latency
a 10,000 rpm fast hard drive [if you really want to spend a few more $$ a 15,000 rpm SAS]
blah blah psu+moboard+video ; would recommend a nicely vented case [& an extra cooling fan (or if you even want to go that extra mile some sort of add-on water cooling apparatus)]

Such a machine comes in under $650 - expect just under $700 with a 300 gig velociraptor ... expect more if you're going to config with an SAS drive [I'd think you'd be better off with a server board+box if you're going the SAS drive route though]

2) I tend to watch the appropriate forums & a few respectable component websites for very nice sales and put my family+friend+personal machines together. The only caveat you have to watch for is some of the return times given for defective products if you do not purchase your system components all at once; tis still very doable by just being sure you can test the components you do purchase. I may buy some extra memory when it's on sale - pop it into existing 4core moboards or a drive etc - if it works - kewl it can sit until I get the other components, if it fails - RMA back and wait for the replacement part(s) to test them.

Hmm not sure if i'll get brow-beaten for including any site links so I'll just mention a few I frequent weekly: overclockers forums (ocforums / cyber deals), hardforum (hot deals), newegg, frys & microcenter have a lot of "b&m" (brick and mortar) only deals besides their online sales.
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