Cost to compute prime
 

Is there any estimate on the cost to LL test 2^43,112,609-1?

[QUOTE=Unregistered;148682]Is there any estimate on the cost to LL test 2^43,112,609-1?[/QUOTE]

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?

[quote=petrw1;148689]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?[/quote]

Then pick your appropriate sub-question(s):

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. :wink:

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.

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.

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

[QUOTE=Unregistered;148682]Is there any estimate on the cost to LL test 2^43,112,609-1?[/QUOTE]

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.

[QUOTE=fivemack;148847]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.[/QUOTE]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

[QUOTE=S485122;148851]150 W of electricity with all cores runninf and the motherboard and...[/QUOTE]

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.)[/QUOTE]

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.

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.

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
[B]RESULTS[/B]

Device 1
Price per day: $3.04
Price per week: $21.29
Price per year: $1110.33
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