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 2008-11-10, 18:52 #1 Unregistered   11010101000002 Posts Cost to compute prime Is there any estimate on the cost to LL test 2^43,112,609-1?
2008-11-10, 19:20   #2
petrw1
1976 Toyota Corona years forever!

"Wayne"
Nov 2006

10010111001102 Posts

Quote:
 Originally Posted by Unregistered Is there any estimate on the cost to LL test 2^43,112,609-1?
Define "cost".

Time it will take?
Cost in Power Consumption?
GHz days of credit?
Cost to your sanity waiting for it to finish and wondering if it will be prime?
Other?

2008-11-10, 21:36   #3
NBtarheel_33

"Nathan"
Jul 2008
Maryland, USA

5×223 Posts

Quote:
 Originally Posted by petrw1 Define "cost". Time it will take? Cost in Power Consumption? GHz days of credit? Cost to your sanity waiting for it to finish and wondering if it will be prime? Other?

How fast is the computer employed to run the test?
What is the cost per unit of electricity supplied to the computer running the test?

And, as for anyone waiting and wondering whether 2^43,112,609-1 is prime at this point...well, their sanity might be already quite a bit in debt, or doubt.

 2008-11-10, 23:02 #4 Uncwilly 6809 > 6502     """"""""""""""""""" Aug 2003 101×103 Posts 2·3·5·337 Posts The intial cost was almost nothing, cents. The computer that found it was already going to be on. The extra electricity was not much. The double checks were likely more costly, but not directly billed to anyone. just my guess.
 2008-11-11, 12:23 #5 hockmeng     Oct 2008 2·7 Posts The cost, be it time or money will depend on the computer you are using. At the moment, it does not seem like the question has provided enough information to obtain an answer.
 2008-11-11, 15:47 #6 S485122     "Jacob" Sep 2006 Brussels, Belgium 110110110012 Posts There are also hidden costs to test the primality of 43 112 609 : it had to be trial factored, P^1'ed and more important the exponents below it had to be processed as well. If it would just be a matter of choosing 43 112 609 and LL test it on a modern computer the marginal cost (not counting the cost of the hardware) is only 8 days of electricity (less than 70 KWh for a quick quadcore with a low consumption graphic card.) Jacob
2008-11-11, 15:51   #7
fivemack
(loop (#_fork))

Feb 2006
Cambridge, England

644410 Posts

Quote:
 Originally Posted by Unregistered Is there any estimate on the cost to LL test 2^43,112,609-1?
A quad-core computer costs $730 and lasts two years, during which time it uses 150W of electricity; so the cost in computer depreciation is$1 per day and the cost in electricity about thirty cents. The LL test took eight days, so call it ten bucks.

2008-11-11, 16:26   #8
S485122

"Jacob"
Sep 2006
Brussels, Belgium

1,753 Posts

Quote:
 Originally Posted by fivemack A quad-core computer costs $730 and lasts two years, during which time it uses 150W of electricity; so the cost in computer depreciation is$1 per day and the cost in electricity about thirty cents. The LL test took eight days, so call it ten bucks.
150 W of electricity with all cores runninf and the motherboard and... It is to low a value, mine 450 W is perhaps a bit high. Also you count 80 days, my quadcores test a 44M exponent in about 30 days on a single core, using all four you should divide by 4 (well 3,2 actually.) About amortisation of a computer 2 years is quite quick, I would say three to four years. I for one have no intention of replacing my QX6700 based computer in january when it will be 2 years old (I must admit it cost more than 730,00 USD at the time.) And your calculation is valid for a GIMPS dedicated computer, not if it is used for other things.

Jacob

2008-11-11, 17:01   #9
fivemack
(loop (#_fork))

Feb 2006
Cambridge, England

22×32×179 Posts

Quote:
 Originally Posted by S485122 150 W of electricity with all cores runninf and the motherboard and...
150W (maybe 160W) is measured from my Q6600 system running heavy number-field sieve jobs. It has no hard drive and on-motherboard graphics, it's running in text mode; the OS is on a USB stick, the filesystems mounted over NFS.

I think my price is for eight days rather than eighty.

Quote:
 About amortisation of a computer 2 years is quite quick, I would say three to four years. I for one have no intention of replacing my QX6700 based computer in january when it will be 2 years old (I must admit it cost more than 730,00 USD at the time.)
I suppose two years is a bit short for amortisation to zero; after two years you can sell the machine for say $180 to an undergrad looking for their first computer. Retention time depends how fast the replacement computers are; I bought a dual-core Athlon64 in the middle of 2007 for £200, and sold it on in the middle of 2008 for £75 to put towards buying a Phenom which is two and a half times faster. I don't see a jump comparable to the dual-core to quad-core one occurring in the near future - the 2010 Westmere processor has six cores.  2013-12-16, 15:03 #10 PhoebeAnn Dec 2013 Central FL 2×5 Posts Real data I'm running a 6-year-old Intel Xeon quad-core machine (Windows 7, 4GB, Radeon HD6570) that I've got about$200 into. Idling power consumption is 114W, running prime95 alone it's 181W. About $69/year for me to leave it running. Thankfully, I don't itemize, so I don't worry about things like that.  2013-12-16, 16:57 #11 flashjh "Jerry" Nov 2011 Vancouver, WA 1,123 Posts One of my systems (that is currently offline): Code: SUMMARY The price of electricity per Kwh: .12675 Hours of use per day: 24 Device 1 uses 1000 watts RESULTS Device 1 Price per day:$3.04 Price per week: $21.29 Price per year:$1110.33 Based on the All kWh above 1,000 including the Fuel charge from here

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