[QUOTE=flashjh;372512]Well, SLI can change the video card numbers. Try using
-d00 and -d01 to start mfaktc.[/QUOTE]That's not the issue. These two cards were working just fine for the last 3 weeks as two independent cards, running mfaktc on both with -d0/-d1, it's only since I messed up the drivers that it fails to run.

edit: SLI enabled or disabled makes no difference, it's failing because of the non-detected CUDA version.

edit2: 337.50-beta drivers also failed to fix anything

edit3: for what it's worth this is what the NVIDIA System Information box says:
[url]http://s11.postimg.org/l5lbe1ber/nvidia.png[/url]

[QUOTE=James Heinrich;372508][code]CUDA version info
binary compiled for CUDA 4.20
CUDA runtime version 0.0
CUDA driver version 0.77[/code][/QUOTE]Hmm... That was for the LessClasses version of mfaktc I've been running as my personal project for the last long while, but on a whim I tried the regular version of mfaktc and it played nice:[code]CUDA version info
binary compiled for CUDA 4.20
CUDA runtime version 4.20
CUDA driver version 6.0[/code]Doesn't solve my problem, and in fact makes me more confused, but it's a new aspect to the problem.

To add more confusion, I tried an old backup installation of mfaktc-LessClasses from 2012, and I got even weirder detected CUDA driver version:[code]CUDA version info
binary compiled for CUDA 4.20
CUDA runtime version 0.0
CUDA driver version 4068.80[/code]

[QUOTE=flashjh;372512]Well, SLI can change the video card numbers. Try using
-d00 and -d01 to start mfaktc.[/QUOTE]For me, at least, with SLI enabled it's weird. Starting any single instance of mfaktc always runs on the second GPU no matter what -d parameter is set. Starting two instances (with -d0/-d1 that works nicely without SLI) makes the system unusable: the GUI is so sluggish it's hard to click on what you want, and GPU usage for the first GPU is solid 100% (presumably overtaxed, hence the slow GUI) while second GPU usage fluctuates wildly between 10% and 90%. It's like both instances are fighting for the first GPU and some leftovers are spilling to the second.

In short, it doesn't play nice. I guess for now I'll keep SLI disabled, I don't really have many (any?) games that benefit from it anyways.

Hi James,

sounds just like a wrong CUDA runtime DLL is loaded.
There is a function inside the runtime DLL which reports the version of it... and it reports bullsh*t when it is not the correct version. I've tried to file a bug against it but nvidia said: "Works as designed, not a bug! Just use the correct runtime version." :sad:
So version detection only works reliable if the correct runtime dll (correct version) is used...
Back to your issue: do you have the CUDA 4.2 runtimes in the working directories?
[LIST][*]CUDA runtime DLL [B]must match[/B] the version used during compile (CUDA toolkit version)[*]CUDA driver must support [B]at least[/B] the version from the CUDA toolkit[/LIST]So for the CUDA 4.20 binary you must use CUDA runtime 4.20 and your driver must support at least 4.20.
Oliver

[QUOTE=TheJudger;372541]do you have the CUDA 4.2 runtimes in the working directories?[/quote]Of course -- I have cudart64_42_9.dll in the LessClasses installation (64-bit, faster for CPU-sieving), and cudart32_42_9.dll in the "regular" mfaktc installation (32-bit, faster for GPU-sieving). Both were working fine for many months, until my latest attempt at driver installation which broke things, apparently.

Compiled for 4.2, got the 4.2 DLL in the folder, and driver supports 6.0

If this was a new driver I might think NVIDIA broke something, but I've been 335.23 since March without problem, until yesterday.
Just to be sure something didn't get corrupted I just copied a mfaktc installation from my other computer, which is happily crunching on my GTX580, but I get the same nonsense (runtime 0.0, driver 0.77).

[QUOTE=James Heinrich;372543]Of course -- I have cudart64_42_9.dll in the LessClasses installation (64-bit, faster for CPU-sieving), and cudart32_42_9.dll in the "regular" mfaktc installation (32-bit, faster for GPU-sieving). Both were working fine for many months, until my latest attempt at driver installation which broke things, apparently.[/QUOTE]

Using 32-bit binaries on a 64-bit OS has been a problem for at least one person in the past:
[URL]https://devtalk.nvidia.com/default/topic/469002/[/URL]

[QUOTE=aaronhaviland;372545]Using 32-bit binaries on a 64-bit OS has been a problem for at least one person in the past[/QUOTE]It's the 32-bit version that runs fine, the 64-bit version that's giving issues.

Hi James,

can you check whether there are other CUDA runtimes (64bit) on your system or not?

Oliver

[QUOTE=TheJudger;372557]can you check whether there are other CUDA runtimes (64bit) on your system or not?[/QUOTE]How? Do you mean like cudart64*.dll? There's a number of them scatted through various directories, including "C:\NVIDIA\" (default unpack location for temp files for driver install), "C:\Program Files\NVIDIA Corporation\Installer2\" (looks like a similar pre-install repository). Not counting stuff I copied manually into GIMPS-related folders, I see (in various places)[quote]cudart64_41_0.dll
cudart64_55.dll
cudart64_60.dll[/quote]Full list (cudart*.dll), if relevant:[code]C:\NVIDIA\DisplayDriver\335.23\Win8_WinVista_Win7_64\English\GFExperience.NvStreamC\cudart32_41_0.dll
C:\NVIDIA\DisplayDriver\335.23\Win8_WinVista_Win7_64\English\GFExperience.NvStreamSrv\amd64\server\cudart64_41_0.dll
C:\NVIDIA\DisplayDriver\335.23\Win8_WinVista_Win7_64\English\GFExperience.NvStreamSrv\x86\server\cudart32_41_0.dll
C:\NVIDIA\DisplayDriver\335.23\Win8_WinVista_Win7_64\English\ShadowPlay\cudart32_55.dll
C:\NVIDIA\DisplayDriver\335.23\Win8_WinVista_Win7_64\English\ShadowPlay\cudart64_55.dll
C:\NVIDIA\DisplayDriver\337.50\Win8_WinVista_Win7_64\English\GFExperience.NvStreamSrv\amd64\server\cudart64_41_0.dll
C:\NVIDIA\DisplayDriver\337.50\Win8_WinVista_Win7_64\English\GFExperience.NvStreamSrv\x86\server\cudart32_41_0.dll
C:\NVIDIA\DisplayDriver\337.50\Win8_WinVista_Win7_64\English\ShadowPlay\cudart32_55.dll
C:\NVIDIA\DisplayDriver\337.50\Win8_WinVista_Win7_64\English\ShadowPlay\cudart64_55.dll
C:\Prime95\cudalucas\cudart64_42_9.dll
C:\Prime95\cudapm1\cudart64_55.dll
C:\Prime95\mfaktc\_archive\1\cudart64_42_9.dll
C:\Prime95\mfaktc\_archive\2\cudart64_42_9.dll
C:\Prime95\mfaktc\_archive\3\cudart64_42_9.dll
C:\Prime95\mfaktc\_archive\4\cudart64_42_9.dll
C:\Prime95\mfaktc\_archive\5\cudart64_42_9.dll
C:\Prime95\mfaktc\_archive\6\cudart64_42_9.dll
C:\Program Files (x86)\NVIDIA Corporation\PhysX\Common\cudart32_60.dll
C:\Program Files (x86)\NVIDIA Corporation\PhysX\Common\cudart64_60.dll
C:\Program Files\NVIDIA Corporation\Installer2\GFExperience.NvStreamC.{49C76DBD-6D64-4E73-8D48-9B7EA264D8B3}\cudart32_41_0.dll
C:\Program Files\NVIDIA Corporation\Installer2\GFExperience.NvStreamC.{E76E2E52-96FD-4075-897B-061FB8C61607}\cudart32_41_0.dll
C:\Program Files\NVIDIA Corporation\Installer2\GFExperience.NvStreamSrv.{0ECD3D52-E3C1-42C9-8A83-B3EC0354FD57}\amd64\server\cudart64_41_0.dll
C:\Program Files\NVIDIA Corporation\Installer2\GFExperience.NvStreamSrv.{0ECD3D52-E3C1-42C9-8A83-B3EC0354FD57}\x86\server\cudart32_41_0.dll
C:\Program Files\NVIDIA Corporation\Installer2\GFExperience.NvStreamSrv.{12B5216B-714A-4831-B4CE-04FD1A0B55D2}\amd64\server\cudart64_41_0.dll
C:\Program Files\NVIDIA Corporation\Installer2\GFExperience.NvStreamSrv.{12B5216B-714A-4831-B4CE-04FD1A0B55D2}\x86\server\cudart32_41_0.dll
C:\Program Files\NVIDIA Corporation\Installer2\ShadowPlay.{A8945935-7B10-4CEE-9F43-777C614EA9DB}\cudart32_55.dll
C:\Program Files\NVIDIA Corporation\Installer2\ShadowPlay.{A8945935-7B10-4CEE-9F43-777C614EA9DB}\cudart64_55.dll
C:\Program Files\NVIDIA Corporation\Installer2\ShadowPlay.{AC36DD82-64BA-4542-A601-0575C7937360}\cudart32_55.dll
C:\Program Files\NVIDIA Corporation\Installer2\ShadowPlay.{AC36DD82-64BA-4542-A601-0575C7937360}\cudart64_55.dll
C:\Program Files\NVIDIA Corporation\Installer2\ShadowPlay.{C7FFF38C-8B7D-4178-A583-1CEFE383AFF1}\cudart32_55.dll
C:\Program Files\NVIDIA Corporation\Installer2\ShadowPlay.{C7FFF38C-8B7D-4178-A583-1CEFE383AFF1}\cudart64_55.dll
C:\Program Files\NVIDIA Corporation\NvStreamSrv\cudart64_41_0.dll
C:\Program Files\NVIDIA Corporation\ShadowPlay\cudart64_55.dll
C:\Users\User\AppData\Local\Temp\NVIDIA\GeForceExperienceSelfUpdate\12.4.55.0\GFExperience.NvStreamSrv\amd64\server\cudart64_41_0.dll
C:\Users\User\AppData\Local\Temp\NVIDIA\GeForceExperienceSelfUpdate\12.4.55.0\GFExperience.NvStreamSrv\x86\server\cudart32_41_0.dll
C:\Users\User\AppData\Local\Temp\NVIDIA\GeForceExperienceSelfUpdate\12.4.55.0\ShadowPlay\cudart32_55.dll
C:\Users\User\AppData\Local\Temp\NVIDIA\GeForceExperienceSelfUpdate\12.4.55.0\ShadowPlay\cudart64_55.dll[/code]

Hi James,

can you (temporary) remove all CUDA DLLs from your mfaktc folder and try again. The symptoms are exactly what I expect when using a wrong CUDA runtime DLL. When you remove all CUDA DLLs from your mfaktc folder and still get the same issues than you can be sure that somehow you're using the wrong DLLs.

This is from mfaktc 0.20 src/mfaktc.c:[CODE]
int drv_ver, rt_ver;
if(mystuff.verbosity >= 1)printf("\nCUDA version info\n");
if(mystuff.verbosity >= 1)printf(" binary compiled for CUDA %d.%d\n", CUDART_VERSION/1000, CUDART_VERSION%100);
#if CUDART_VERSION >= 2020
cudaRuntimeGetVersion(&rt_ver);
if(mystuff.verbosity >= 1)printf(" CUDA runtime version %d.%d\n", rt_ver/1000, rt_ver%100);
cudaDriverGetVersion(&drv_ver);
if(mystuff.verbosity >= 1)printf(" CUDA driver version %d.%d\n", drv_ver/1000, drv_ver%100);

if(drv_ver < CUDART_VERSION)
{
printf("ERROR: current CUDA driver version is lower than the CUDA toolkit version used during compile!\n");
printf(" Please update your graphics driver.\n");
return 1;
}
if(rt_ver != CUDART_VERSION)
{
printf("ERROR: CUDA runtime version must match the CUDA toolkit version used during compile!\n");
return 1;
}
#endif
[/CODE]
This is the first call the any CUDA related function in mfaktc.

Oliver

[QUOTE=TheJudger;372606]can you (temporary) remove all CUDA DLLs from your mfaktc folder and try again.[/QUOTE]That gives a totally different type of error: a Windows popup error box saying[quote]The program can't start because cudart32_42_9.dll is missing from your computer. Try reinstalling the program to fix this problem.[/quote](Same thing for 64-bit version, with cudart64_42_9.dll). mfaktc doesn't start at all, no CLI output, just the Windows popup.

With the DLLs in the folder then mfaktc starts and complains with my previously-reported errors about CUDA versions. Without them mfaktc doesn't start at all.