Brian's Blog

…one man's contribution to the Weeeeerly Wild World

SETI@home efforts – October

September saw me powering up my small hoard of computers and getting them crunching again after being left abandoned for the warm summer months. I basically had to strip down and rebuild four computers, cleaning out dust, and then juggling graphics cards with power supplies – my Nvidia 680 had a slight hiccup in the process but that resolved itself, and I got my 550W PSU to power two 460s… for a while at least.

One GPU down (after all)

Sadly, during some shuffling of my twin 460 rig, one of the graphics cards decided to stop working – it powers up but there is no display output, and it wont crunch. I think this was down to me not being so careful with the shuffling, since that card was strapped to a piece of wood with cable ties, and then strapped to the side of the case and linked to the PCI-express socket via a rise cable, similar to this (it keeps the cards cooler when one is out of the case):

seti_dual_gpu

So after having the luck of the 680 almost dying and then not, I have still ended up being a GPU down… but luckily it’s “only a 460” – relatively inexpensive, not so efficient or a great cruncher compared to newer cards.

Ironing out the invalids

I mentioned in my last SETI@home update that I was having trouble with one of two “identical” Nvidia GTX 560ti’s that was producing a lot of Invalid results. After posting in my team’s forums (GPPUG) it was suggested to me that lowering the GPU and/or memory clock speeds to Nvidia’s stock speeds (from the manufacturer’s overclock) may help. After researching this and what I needed to do to achieve this I have succeeded in ironing out the invalids – I have also tweaked some other graphics cards and reduced invalids produced by other rigs. Here is what I did:

  • I installed OCCT (DirectX is required), and with the Error Check box checked I clicked ‘On’ to run a test.
  • Within 10 seconds lots of artefact errors were being reported on the problematic graphics card.
  • I installed MSI Afterburner and lowered the GPU Core Clock from 900 to around 830MHz for this graphics card, and Memory Clock from 2098 to around 1660MHz.
  • I re-ran the OCCT test for a few five minutes and no artefact errors were reported – confirming the card is ok at ‘reference card timings’.
  • I then played with various timings between those two extremes and tested for 5 minutes with each until I settled on the lower GPU Core Clock of 830MHz, and original supplied Memory Clock of 2098 – the testing confirmed Palit’s overclock of the GPU for this card was causing the artefacts.
  • I’ve now instructed MSI Afterburner to apply my settings at startup and I will keep an eye open for further Invalids.

Overclocking is a good way to get the most out of your equipment but if you get (too many) errors then you lose this advantage. Overclocking also mean things run hotter, fans run faster, consume more energy, and likely shorten the lifespan of part – so you have to way up the benefits.

Progress in October

Throughout October my RAC (Recent Average Credit) increased from 25K to 50K where it has now plateaued – I’m still not leaving all rigs on 24/7 as I’m just using them to keep rooms warm during the day, and leaving my house nice and quiet during the night.

seti_oct2015

I’m now just scraping in the Top 20 in the team I’m in (GPUUG). I still want to make more headway in the UK rankings – I’m currently 7th in the Total Credit list, but not yet in the Top 10 with my RAC at less than 50K. According to BOINCstats it will take me over a year to overtake the person (Gone) currently in 6th who is no longer participating, and I’m soon to be overtaken by someone who’s RAC is 4x higher than mine – even with all my computers on 24/7 I can do nothing about that, so until then I will drop to 8th.

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One comment on “SETI@home efforts – October

  1. Pingback: SETI@home efforts – January | Brian's Blog

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This entry was posted on 7 November, 2015 by in Computers, SETI@home and tagged , , , , , .
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