GPU Trial Factoring FAQ

[Dubslow]

Nah, hear is fine. The HD 5570 might still be good for mfakto, you'd have to check the PDF in the original post to see what mfakto requires.

In general, CUDA is more efficient compared to OpenCL as far as getting the most actual performance out of theoretical ops/second; James maintains a chart, visible here, that contains theoretical performance and estimated GIMPS performance for a variety of cards. Note that for the ratio of GHz-Day/Day to GFLOPS is much higher than with AMD, going back to CUDA vs. OpenCL. (Compare the 6990 to the 590, which are supposed to be roughly equivalent cards in most respects.) Since price is generally correlated to GFLOPS (as opposed to GIMPS throughput), nVidia is probably more value if you're just looking for value. If you do go with nVidia, be sure to get a "Compute Compatibility" 2.0, and NOT 2.1. The 580 might be within your price range given that the 680 has just come out, but I'm not sure. If not, I'd go with a 570. Unfortunately, because the AMD cards are less efficient in relation to GIMPS, I can't tell you too much about them.

As for power, you're right to not be worried at all. My quad core 3.4 GHz 2600K has a TDP of 95W, not much more than a lightbulb. Together with the GTX 460 and all the other stuff, I use a 600W power supply, though it's likely that the comp doesn't draw more than 450W, even with everything under full load. One of the reasons we have quad core computers for the same size as those old single cores is because the transistors are much smaller (today's transistors are more than an order of magnitude smaller than the wavelength of visible light), which means they also draw a lot less power to do the same thing. (Ivy Bridge will feature 77W TDP quad cores at slightly higher frequencies than Sandy Bridge, thanks to a transistor shrink and redesign.)

[Dubslow]

Okay, regarding TF on AMD cards, this thread has made it clear that the original post is not clear enough on how to use AMD cards.

For simplicity's sake, here are some example changes:

Q. Can I use my GPU to trial factor Mersenne numbers?
A. If it is a relatively modern GPU, yes. You can see the list of Nvidia supported GPUs here: http://en.wikipedia.org/wiki/CUDA#Supported_GPUs , and the list of AMD supported GPUs here: http://www.khronos.org/conformance/adopters/conformant-products/

Q. So what software do I use and where do I get it?
A. For nvidia based GPUs use mfaktc http://www.mersenneforum.org/mfaktc .
For other GPUs (including AMD/ATI), use mfakto, an OpenCL implementation. The latest version is here: http://www.mersenneforum.org/showthread.php?t=15646 . You can also check the PDF attached to this post; it contains the most recent versions, specific compatibility requirements, as well as examples of how to use the programs.

A new question, to be inserted directly proceeding the above two:

Q. How do I use these programs?
A. The programs are run from the command line (cmd.exe in Windows). Open a command line, change to the right directory, and run "mfaktc.exe -h" or "mfakto.exe -h". It is also possible to set up shortcuts, batch files, or shell scripts to automatically start mfakt* after you have learned how to use the program. Again, see the attached PDF for more detailed usage examples.

It might also be worthwhile to add more emphasis to the "mfaktc uses CPU" question, as we've had at least one user post wondering if that was right since the thread went up.

[jasong]

Thanks dubslow, I'll repost if I have any problems. Your info should keep me busy for a good long while. :)

Edit:chrisjp, apparently the creater of the program, says you have to fight with the program to get this version running properly, so I think I'll just watch these threads and track progress for the moment.

Thanks for the help. I'm gonna go look at the last few weeks of the posts for these threads and then call it a night for this particular goal.

[Dubslow]

...Which program? mfakto was written by Bdot.

[Bdot]

Originally Posted by jasong

Thanks dubslow, I'll repost if I have any problems. Your info should keep me busy for a good long while. :)

Edit:chrisjp, apparently the creater of the program, says you have to fight with the program to get this version running properly, so I think I'll just watch these threads and track progress for the moment.

Thanks for the help. I'm gonna go look at the last few weeks of the posts for these threads and then call it a night for this particular goal.

Let me suggest you start with the 5570 you have, install the latest Catalyst (i.e. AMD graphics) driver, and play around a little with mfakto.

James' site suggests that you can get ~30 GHz-days per day with that. If you kind of like how that works, you just want it faster, then use that table again (for instance) to find a GTX570 can be 10 times as fast (if you have the CPU power to feed it well).

And if you could send to James a benchmark run of the 5570, you can help making the table more accurate so that similar predictions will be better.

[LaurV]

Someone should actualize the links to the newest pdf and mfaktc/o.
edit: i mean, in the first post.

[petrw1]

Does that sound kinky?

Anyway getting suspicios errors:

running a simple selftest...
ERROR: cudaGetLastError() returned 6: the launch timed out and was terminated

This is after about 45 seconds at which time the screen goes blank and then Windows7 64-bit pops up a window in the taskbar that says something like: Display Driver stopped responding and was recovered.

Only one time out of about 7 tries it did pass the selftest and then said it could not read the worktodo.txt file.

2 questions:

1. I assume it should be in the same directory as the mfaktc?
2. From the readme there is this sample line: Factor=bla,66362159,64,68
Is the bla, required?

Per James suggestion I changed Numstreams to 2 but my GUI is still quite laggy.

[Dubslow]

Yes, they should be in the same directory. No, the bla can be anything or nothing.
Factor=bla,66362159,64,68 works as well as Factor=66362159,64,68 works as well as Factor=N/A,66362159,64,68 works as well as Factor=<long hex key>,66362159,64,68. For your errors, I'd look into what the various CUDA versions you're using. That card is only CC 1.1, which is probably causing errors with the software you're using; I'll look into that, brb. (QuickEdit: The not finding worktodo.txt may be a permissions thing; it's best if your mfaktc folder is inside your User folder, or My Documents.)

Edit: Okay, here's something from Makefile.win:

NVCCFLAGS = -m64 --generate-code arch=compute_11,code=sm_11 --generate-code arch=compute_20,code=sm_20 --ptxas-options=-v

With a no knowledge of nVidia compiler options, I'd hazard a guess that this means that the binaries provided in the mirror do have CC 1.1 code somewhere in them. nVidia does supposedly offer backwards compatibility, meaning that code compiled for CC 1.1 ought to run with later versions of CUDA, i.e. later versions of the .dll's, so I'm not sure what the problem is. I'd take this to the mfaktc thread.

[Karl M Johnson]

That error is related to WDDM.

Create patch.reg, paste the code below in it and run that as admin:

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\GraphicsDrivers]
"TdrLevel"=dword:00000000

[Redarm]

First time i'm posting...
I've get a GTX 680 and have absolutely no idea how to get mfactc0.18 running :(

ERROR: cudaGetLastError() returned 8: invalid device function

I've readed something about compiling with Cuda Toolkit 4.2 but have no clue how to do this, could someone help me please?

[Dubslow]

You shouldn't need to compile anything... What OS? What are the version numbers of the .dll/.so files you're using?