20130314, 02:57  #221 
Romulan Interpreter
Jun 2011
Thailand
8635_{10} Posts 
Unknown. Some people do "in house" double checks before reporting CL results, and "spidering" won't help. I have about 10% error rate for the tests I do. I never counted exactly, but I still remember FebMarch 2012, when CuLu changed to nonpowerof2 FFT and the intermediary versions used to give wrong residues, after that date I always run two copies of CuLu in two different cards, and maybe with two different FFT sizes, and report the result only if I have a match. This is still faster than using P95 in the loop, and anyhow it will need a third party to do the DC. So, the results reported to the server are not relevant. Also, if someone only do DCLL, they won't report mismatching results, and they will TC first.
For me, running in parallel allows me to catch the error in the earliest phase, and save the time which would be wasted if the test is allowed to finish. When I have two non matching residues, I redo both from the last saving. From my experience, with overclocking (water cooled) the errors are around 10%, maybe more. Without overclocking the value is much lower, maybe 2% or so, but I am still not confident enough to giveup "inhouse double checking". The 10% can look a lot, but you have to think about the fact that if you test 10 exponents of 50M, then you do 500M iterations, and if only one iteration in those 500M is wrong, you got one of your 10 expos wrong, so here is your 10%. There is no mystery into it. For me the real mystery is how P95 (and the CPUs in general) can do 500 MILLIONS iterations, without getting any of them wrong.... 
20130314, 08:15  #222 
Banned
"Luigi"
Aug 2002
Team Italia
11·433 Posts 
I am running DC and LL on my cards. Since I started, I only had 3 nonmatching results, two of them were subsequently found correct.
Luigi 
20130314, 10:24  #223  
Einyen
Dec 2003
Denmark
B4B_{16} Posts 
Quote:
Quote:
Last fiddled with by ATH on 20130314 at 10:25 

20130314, 11:43  #224  
Mar 2003
Melbourne
1003_{8} Posts 
Quote:
The reduction in performance was about 10+% ish. Given it takes a long time to verify stability, as LL double checks seem to be the only reliable way to verify. I'm too lazy to fiddle to optimize ram speed. (It's going to take a while :) )  Craig 

20130314, 16:05  #225 
Apr 2012
Berlin Germany
3·17 Posts 
2900 mhz produces errors (3.1ms per I M48)
2750mhz seems stable for now (3,35ms per I M48) 
20130314, 16:42  #226 
Jul 2003
So Cal
2^{3}×11×23 Posts 

20130314, 16:47  #227  
Einyen
Dec 2003
Denmark
7^{2}×59 Posts 
Quote:


20130314, 17:52  #228 
Apr 2012
Berlin Germany
3×17 Posts 
found a way to find errors produced by vram
instructions coming soon ... (memtestg80 is essential) 
20130314, 19:32  #229 
Dec 2009
Peine, Germany
331_{10} Posts 
100M
2500MHz VRAM = 2070h:
Code:
E:\Eigene Dateien\Computing\CUDALucas\2.03\D0>CUDALucas2.035.0sm_35x64.exe threads 512 f 20971520 t 332192831 Warning: No ini file detected. Using defaults for nonspecified options. Starting M332192831 fft length = 20971520 Iteration 10000 M( 332192831 )C, 0x7e591d0cbd938d73, n = 20971520, CUDALucas v2.03 err = 0.0332 (3:44 real, 22.4112 ms/iter, ETA 2067:55:55) Iteration 20000 M( 332192831 )C, 0xc2eda19e28f00bf4, n = 20971520, CUDALucas v2.03 err = 0.0339 (3:44 real, 22.4587 ms/iter, ETA 2072:14:52) Iteration 30000 M( 332192831 )C, 0x4e96b2da36fcce56, n = 20971520, CUDALucas v2.03 err = 0.0352 (3:44 real, 22.4425 ms/iter, ETA 2070:41:49) 
20130314, 19:38  #230 
If I May
"Chris Halsall"
Sep 2002
Barbados
3^{2}×1,019 Posts 

20130314, 21:02  #231 
ἀβουλία
"Mr. Meeseeks"
Jan 2012
California, USA
100001101111_{2} Posts 

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