LHC@home

It would appear from my abysmal record on this machine which, while overclocked, does very well on Rosetta, Einstein, and many other projects, is not appropriate for this project! Even one of the "pending" units waits in limbo while all the others have already received credit! ;)

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Regards,
Bob P.

:-) Lucky you ;-) mine used to give client error when i was over clocking.
Regards
Masud.

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I believe LHC is much more sensitive to floating point errors than other projects. They have even had problems with the slight differences between the way Intel and AMD implement floating point math. Your overclocked CPU is probably returning slightly incorrect results on other projects as well but they match closely enough that you still get credit. The thing with LHC is that if the first calculation is off by even 0.0000[...]001 then by the end you are way off because later calculations are all based on previously calculated numbers.

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- A member of The Knights Who Say NI!
My BOINC stats site

I believe LHC is much more sensitive to floating point errors than other projects. They have even had problems with the slight differences between the way Intel and AMD implement floating point math. Your overclocked CPU is probably returning slightly incorrect results on other projects as well but they match closely enough that you still get credit. The thing with LHC is that if the first calculation is off by even 0.0000[...]001 then by the end you are way off because later calculations are all based on previously calculated numbers.

I too have an overclocked system and am getting a 50% invalid ratio at this point with LHC. I don't think that this happened before the move to the UK, but yes, I realize that with extended time of overclock/overvolt, problems can begin to happen...

Question to Alex/Neasan:

Are the validators the same as what they were before the move, or has there been any change made to the validator code?

I have two OC machines attached, and they are doing just fine. No validation problems at all.

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Dublin, California
Team: SETI.USA

My Athlon 2800, which is OCed to about 3600, does fine on every project i have it working for. although i have noticed that if i try to play a game, when the cpu is currently crunching a LHC WU it inevitably causes it to error out. LHC is the only project that this happens for. so it seems that LHC WUs are a great stability test for your CPU. i had mine up to 3800, crunched away nicely until it got LHC WUs then it errored all of them. i dropped the clock and everything is back to normal, except when i play games of course :)

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It is the same validator as before the move. As mentioned LHC@home is uber-sensitive to slightly mismatched results so over clocking can affect validation for some people it works and some it doesn't this was the case before the move and is still the case now.

I have just started using LHC but on World Community Grid if my cpu temp goes over 130F then I start getting errors on about 1 out of 4 results. Better cooling may sovle your problem.

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depends on definition of overclock...

I've never own'ed an AMD 3200+ cpu, it has always been an:
AMD 2500+ 333mhz.
I got lucky with an underclocked model, and with 2 jumpers in the cpu socket,
I got it to run at 400mhz bus speed, and because the mutiplier is the same as
that of the 3200+, all is good. (not even a temperature increase :D )
I did much checking when I started, every time I had a glitch, but it always
turned out to be a software issue; so it remains um, boosted.
I did nothing else, and not a program yet has stated it to be anything other
than a 3200+. (was glad I bought all 400mhz ram, yet the system could run
the ram at 333 if need be.)

While I'm on odd things, the Kingston ram for this system CL3 does not work;
maybe due to the Corsair being CL2.5 @ 400mhz...
... So I was given a Kingston CL2.5 to try, even though my mobo ain't on its
list, and it works.
I now have 3 x 512, 1 Corsair, 2 Kingston, at CL2.5 @ 400mhz with 2.2 ghz cpu.

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