mersenneforum.org Athlon prime, strange results
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 2005-01-16, 00:24 #1 madbullet   Jan 2005 23 Posts Athlon prime, strange results hi, i posted in the hardware section that i was having failings in all tests of prim. now ive tested the athlon version i have some strange results both Blend and In-place large FFT's fail instantly, how ever the Small FFT's doesn't. could someone with some knowledge tell me what could be the problem, someone did reply in the previous post o say that it could be a bad CPU because FFT's stress the CPU more (or some words to that affect) thanks
 2005-01-16, 03:04 #2 Prime95 P90 years forever!     Aug 2002 Yeehaw, FL 32×823 Posts 98% likely that it is memory. Small FFTs run out of the L2 cache, blend and in-place must access main memory. Try memtst86. Try slower RAS, CAS, etc. timings. Try just one stick of memory instead of two. Try slower FSB.
 2005-01-16, 04:24 #3 cartmanea   Oct 2004 Corvallis, OR 2·5 Posts I'm getting the same results and my memory passes countless loops of Memtest86. I've had the problem for about 9 months now and its really driving me insane. I've tried re-downloading Prime95 too, thinking my copy was maybe corrupt, still a no-go. I've also tried 3 different motherboards, both amd and p4, and 4 cpu's, all with the same results. I've also tried lowering my fsb, which makes it last longer but it eventually fails. Could it be my memory even though Memtest86 doesn't find any problems? Please help, I'm about bald from pulling all my hair out!
 2005-01-16, 08:09 #4 ben   Jan 2005 11 Posts On SCO OpenServer 5.0.6, Pentium 4 Xeon 2.4GHz CPU, 4GBytes Memory. I compile Mlucas with gcc-2.95.2: $gcc -o Mlucas -static -O3 *.c -lm Then run Mlucas -s m also was having failings in large FFT test, but the Small FFT's doesn't. If not optimize:$ gcc -o Mlucas -static *.c -lm Then all test pass, but speed is slow. I compile Mlucas with gcc-3.4.3: \$ gcc -o Mlucas -static -O3 *.c -lm Then all test pass, speed is fast. see http://ben.skyiv.com/test/Mlucas.htm Thus, this is relate to compiler and optimize. Last fiddled with by ben on 2005-01-16 at 08:15
 2005-01-16, 16:16 #5 madbullet   Jan 2005 810 Posts hey cartmanea what Memtest are you using? im using memTest86+ version, which should an error (so MR prime was right aboutthe memory, give the man a drink ) i did use Memtest (non +) at first and didnt show any results. if its like mine then it'll be the RAM (although i haven't been able to change it yet, all my test do indicate its a memory problem) so try the + version of memtest and see what happens. thansk for all those who were kind enough to respond to my posts
 2005-01-16, 21:58 #6 cartmanea   Oct 2004 Corvallis, OR 2×5 Posts I used the latest version of Memtest86+
 2005-01-17, 01:46 #7 madbullet   Jan 2005 23 Posts have you tried (if u can) a different stick of RAM? you say if tried different motherboards and CPU's so thats rules them out. change hardware one by one to see what the problem is, of course this is made alto easier if you have friends with spare parts. good luck
 2005-01-17, 02:52 #8 cartmanea   Oct 2004 Corvallis, OR 10102 Posts I found the problem...... One of my sticks of BH-5 had a surface mount capacitor broken off. Its small and VERY hard to notice. Memtest86+ still fails to show any errors, even when I test that stick alone, but Prime95 points the problem out right away. I guess that tells us all something about Memtest86 Last fiddled with by cartmanea on 2005-01-17 at 02:53
 2005-01-17, 05:11 #9 geoff     Mar 2003 New Zealand 115710 Posts Interesting. I guess memtest86 doesn't put enough load on the rest of the system to make this capicitor necessary.
 2005-01-17, 06:22 #10 cartmanea   Oct 2004 Corvallis, OR 2·5 Posts I guess so, or maybe memtest86 doesn't store data in the memory for long periods of time and this capacitor helps keep the charge up so it maintains memory.
 2005-01-17, 14:16 #11 madbullet   Jan 2005 23 Posts OO, well thats very interesting, ive been trying to find another Memory only stress test, but haven't found much, does anybody know if a good memory only stress test? glad to see you found you problem .

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