SETI@home News Vol. 113 (22/08/2010)

Soldato
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That is mean, have seen these things in action, not to far from the coast and i take a trip over some sundays just to watch them on the sand amazing stuff.
I can actually see an upgrade on that costing the same if not more than a 470 or the like very nice M :D
 
Soldato
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Now you should know me by now, come midnight i get tired and a bit silly, i know what you mean mountain bikes are a packet but any idea how much i just laughed when saw "oooooh a downhill bike" or is it just me :D:D;)
 
Soldato
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OK, its early days, but I think after 2 days of testing that I might have got to the bottom of my GPU workunits taking 40-50 mins.
I went down the whole reducing clock speeds route, which did diddly squat..
Watching the task manager, all 4 cpu's were maxed out 100%, and the clue came from watching the load time for the cpu to pass a wu to the gpu, on some wu's, it was taking 2 mins before I saw any sign of crunching. This coupled with some earlier comments over gpu usage levels (mine were all over the place!) made me think that the cpu was possibly the cause
Playing around with the <avg_ncpu> value, it would seem that the long workunit times was down to a cpu bottleneck, one cpu couldn't keep the gpu's fed fast enough.
After playing around with multiple wu/card combo's I have set the following

<avg_ncpu>0.223333</avg_ncpu>
This means I have 2 cpu's crunching and 2 feeding the gpu's

I lose an additional processor, but in 12 hrs I have not had a wu take longer than 28:49 :pat stock clocks
Task manager is showing average cpu usage of around 92-95%, that is with 2 cpu cores crunching and 2 feeding the gpu's which are running 3 wu's each
My gpu usage is also steady at around 92%

This means that I have slightly more playing around with the <avg_ncpu> value as there is a 5% headroom, which is wasted at the moment.
I will of course be ramping the clocks on the gpu right back up to the 800's as soon as I can..

Thank god for that - it was really bugging me!

Toxic - you can give loudbob a slightly gentler slap now as Im in a good mood again
 
Soldato
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Nice one Edge glad to see you got that sorted, could tell it was driving you crazy!
I allways use <avg_ncpu>0.20</avg_ncpu> for 2 or 3 tasks per gpu, but anyways tis sorted, now you can get back to plotting your next move :)
Thought i had got myself a q6600 and board at a good price yesterday but the guys main rig has conked out, am still browsing and undecided what to get - i am driving myself nuts, and the guys at oc :)

Good job i am not in a rush :eek:

 
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Associate
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Well, it looks like it was a heat issue for me. I have a 14" desk fan on full tilt pointing into my case - and I now have two functioning GPUs :D. Clearly this is not sustainable - there are limits as to what I'm prepared to do for SETI - and I would like to able to use my mouse with my left hand thank you very much! :rolleyes:

Looks like a busy week for me next week - loadsa shiney new things in cardboard boxes to bolted on and plumbed in!!!!! :D:D
 
Soldato
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Nice one Area51, hope you might be doing a build log so i can take some pointers. I am just not ready to do the watercooling thing yet, as soon as i get what i want working as i like, and i know it inside out then i may begin.
 
Associate
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Nice one Area51, hope you might be doing a build log so i can take some pointers. I am just not ready to do the watercooling thing yet, as soon as i get what i want working as i like, and i know it inside out then i may begin.

Well, I've taken the blunderbuss approach.:eek: I'm doing two separate loops, one for each GPU. That way, each GPU has its own rad, pump and reservoir. The CPU is staying on the H50. I took this approach so that I have a lot of redundancy and avoid getting into serial/parallel flows, flow balancing, or (good grief, the list goes on) primary/secondary rads etc etc. Yes it works out more expensive, but in the long run, I think this approach will pay dividends when I start messing around with different types of cards. I'll happily do a build log - only if people PROMISE not to laugh!!!!! :o
 
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