GPU LL Questions
 

I am interested in using my GPU for first time, WR LL testing. I have an NVIDIA Geforce GT 620. I scanned the FAQ thread but I didn't read all 12 pages and did not see the answers to my questions there and so I thought I would ask them in a new thread. I apologize in advance for my ignorance regarding GPUs. They are not exactly my most knowledgeable area!

I have a liquid-cooled system and a 3.6 GHz i7 3820 overclocked to 3.8 GHz running four LL tests in the 55.6M range (will be WR once they finish current assignments). CPU temps are running at about 51 to 54 Celsius consistently but sometimes get to 56-58.

How many exponents can I test on the GPU simultaneously? Am I reading the information correctly to assume that a 60M exponent will take about 6 days on a low-medium end GPU?

Will my system see much harm in running P95 on the CPU and also using the GPU?

Thanks!

Kyle

I have downloaded both CUDALucas and the cudart64.42.9.dll. I also had to download 7-zip to open the latter program. I extracted cudart; however, I still cannot open CUDALucas. When I try, I get an error message saying that cudart64.42.9.dll doesn't exist on my computer.

What am I doing incorrectly?

[QUOTE=Primeinator;348792] Am I reading the information correctly to assume that a 60M exponent will take about 6 days on a low-medium end GPU?

Thanks!

Kyle[/QUOTE]
I think your estimate is off; it might take 5-10 times longer than you estimate, depending on what flavor 620 you have.
Look [URL="http://www.mersenne.ca/cudalucas.php"]this page[/URL] over at mersenne.ca for details.

I haven't found this forum to be too hostile toward repeated questions. Something I am rather grateful for myself. I will be following this thread quite closely as I may be using a GPU for LL tests soon also.

I would have thought six days would be right. Wasn't Curtisc's last prime checked out with an Nvidia GPU in three days, allegedly?

[QUOTE=TheMawn;348799]I haven't found this forum to be too hostile toward repeated questions. Something I am rather grateful for myself. I will be following this thread quite closely as I may be using a GPU for LL tests soon also.

I would have thought six days would be right. Wasn't Curtisc's last prime checked out with an Nvidia GPU in three days, allegedly?[/QUOTE]
The people who doublechecked it included someone who used it to check on a gpu.(580)

EDIT: flashjh

[Quote]I would have thought six days would be right. Wasn't Curtisc's last prime checked out with an Nvidia GPU in three days, allegedly?[/QUOTE]

Depends on the GPU; the fastest is like 50x faster than the slowest.

[QUOTE=sdbardwick;348798]I think your estimate is off; it might take 5-10 times longer than you estimate, depending on what flavor 620 you have.
Look [URL="http://www.mersenne.ca/cudalucas.php"]this page[/URL] over at mersenne.ca for details.[/QUOTE]

Thank you for your reply. I assume that because my drivers/devices does not put a version 2 by my GPU that it is version one. Regardless of the version, LL testing appears to take MUCH longer on the GPU than my CPU. Guess I should have gone with a better model.

On a 60M+ exponent:

- On a 580, depending on your card, clock, system, expect a time of 80 to 120 hours.

- On a 620 v2, depending on your card, clock, system, expect a time of 600 to 900 hours.

- On a 620 original, depending on your card, clock, system, expect a time of 1200 to 1800 hours.

Edit: this is not a joke, Keplers have 24 to 1 ratio of single vs double precision floats, they might be better at gaming or TF (depending on model, your mileage may vary), but they are lousy at LL. You can check for yourself how long time per iteration it needs, and see the ETA. If you do, you may post here so we know for sure in the future.

[QUOTE=LaurV;348818]On a 60M+ exponent:

- On a 580, depending on your card, clock, system, expect a time of 80 to 120 hours.

- On a 620 v2, depending on your card, clock, system, expect a time of 600 to 900 hours.

- On a 620 original, depending on your card, clock, system, expect a time of 1200 to 1800 hours.

Edit: this is not a joke, Keplers have 24 to 1 ratio of single vs double precision floats, they might be better at gaming or TF (depending on model, your mileage may vary), but they are lousy at LL. You can check for yourself how long time per iteration it needs, and see the ETA. If you do, you may post here so we know for sure in the future.[/QUOTE]

This is pretty much what I gleaned from the chart (only slightly worse). Too bad. I would have loved to included my GPU in the efforts. I am thinking about getting a box with multiple CPUs or GPUs at some point in the future (nothing high end) but something that would be cost effective for testing lots of exponents at the LL wavefront). I need to do more research to see what would be best.

Thank you for your input and assistance.

Note that 6xx/7xx boards have 1/24 reduced speed when using double precision. = CudaLucas..

For single precision = TrialFactoring MfactC,, its great.. so better use it to trial factor instead.

My 2x Titans has 1/3 reduced speed, and with 2680 cudacores, the latest 55m exponents is done in 60-65 hours. (believe it or not, it depends on the weather outside, as when room is warm, core clock goes down).

The 580 and 590 has 1/8 reduced speed.. with fewer cuda cores this architecture can easily compete with 680 and 690 since its not 1/24 speed with more cudacores.

Therefore I am purchasing second hand 590 boards right now from the local market.. as one 590 board = 2 fermi cores on same board can do the same over time as one Titan board.

Pardon my ignorance... but why is this better if 1/24 is smaller than 1/8. Wouldn't a "1/8" speed reduction in the 590 be worse than the "1/24" reduction?