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2015-05-07, 20:15   #56
chalsall
If I May

"Chris Halsall"
Sep 2002

2·5,023 Posts

Quote:
 Originally Posted by xilman Shipping is likely to cost markedly more than the hardware
Atoms vs. bits...

Perhaps the manufacturer will outsource for those "far away"? (Very likely if those who "pledge" state this as a condition.)

 2015-05-15, 17:20 #57 Xyzzy     Aug 2002 61·137 Posts
 2015-06-09, 21:07 #58 fivemack (loop (#_fork))     Feb 2006 Cambridge, England 22×32×179 Posts On keeping things cold I have a Xeon D-1540 machine now. It's in a nice small case - https://twitter.com/fivemack/status/608362123924774912 - it's nice and quiet, and it overheats if I try running more than a trivial load. Looking at it with a thermal camera, the hotter bits are the AST2400 lights-out-management chip, the i350 dual gigabit PHY, and two components marked VITEC PR72-221 right next to the CPU which are 45-amp 220-nanohenry inductors. Balancing a spare 92mm case fan on top of the heat sink helps a bit - the temperature converges to 60C or so with four threads sieving, but with sixteen threads active it rises at about 0.2C/second. I have an EC3838M fan that I bought from Maplin, which is a 38mm cube that runs at 8000rpm, is advertised as 11 cubic feet per minute, and does manage to keep the temperature static at 68C with forty threads running, but it's just balanced on the heat sink and I can't see how to attach something like it more firmly. Picture of the contraption at http://www.chiark.greenend.org.uk/~t...rver-photo.JPG Any advice? Lots of companies offer big slow fans, but this feels like a situation where I want a fairly small (the heat sink is about 60mm on a side) super-fast fan. Last fiddled with by fivemack on 2015-06-12 at 00:08
 2015-06-09, 21:36 #59 fivemack (loop (#_fork))     Feb 2006 Cambridge, England 144548 Posts Xeon D-1540 benchmarks echo "(10^71-1)/9" | ecm -c 1 1e6 1.220/0.740 seconds for one thread 1.276/0.876 seconds for each of eight threads running simultaneously Comparable job on a C2750 was 2.766/1.925 seconds, so this machine is about 2.5 times the speed. On i7/4770, 0.740/0.536 for one thread and 0.828/0.564 for each of four; so this machine is about 60% the speed, which seems not unreasonable since it's running at 2.4GHz and the i7/4770 at 3.6 or so.
 2015-06-09, 22:03 #60 kladner     "Kieren" Jul 2011 In My Own Galaxy! 2×3×1,693 Posts I realize that you are in the UK, but perhaps you could use this site to track down models to look for.
2015-06-10, 03:09   #61
LaurV
Romulan Interpreter

"name field"
Jun 2011
Thailand

24×613 Posts

Quote:
 Originally Posted by fivemack I have a Xeon D-1540 machine now.
Wow! You have a freaking big foot!

 2015-06-10, 20:33 #62 fivemack (loop (#_fork))     Feb 2006 Cambridge, England 22×32×179 Posts This may not in fact have been Supermicro's best motherboard. 30 watts at idle, 83 watts running sixteen threads of msieve. Do I have just to expect that level of idle power consumption as a side effect of having 32GB of DDR4? I am surprised that gigabit-ethernet PHYs still take noticeable power.
 2015-06-11, 15:30 #63 chris2be8     Sep 2009 89616 Posts Can you change the heat sink? One with fan mountings or a built in fan would help. Or a water cooling system (LaurV posted pictures of his recently). Chris PS. The server photo is at http://www.chiark.greenend.org.uk/~t...rver-photo.JPG (http://chiark.greenend.org.uk/~twomack/server-photo.JPG gets an error message).
 2015-06-12, 00:21 #64 fivemack (loop (#_fork))     Feb 2006 Cambridge, England 22·32·179 Posts I've asked Boston Micro, who sold me the motherboard, to try to figure out the Supermicro part number for the heat-sink-with-fan that they use on the version of the board that has 10Gbit Ethernet, and see if they can order one of those as a replacement for the current heat sink. FCBGA 1667 is a 37.5-mm-square package, which sounds as if it's probably a standard size (and has a integrated heat spreader, which makes me much less worried about breaking it while changing the heatsink); looking at the picture of the motherboard in the manual, and scaling by the length of the DIMM slots, the heat sink is 6cm square and the mounting seems to be with screw-holes with the centre-to-centre distance being 54mm; is that a standard heat-sink size and fixture? Last fiddled with by fivemack on 2015-06-12 at 00:21
 2015-06-14, 09:24 #65 fivemack (loop (#_fork))     Feb 2006 Cambridge, England 22·32·179 Posts Xeon-D linear algebra timings This is on a 4.8M matrix from a C152 Code: Threads | million dimensions per day | total runtime | efficiency 1 3.2 36:34 (100) 2 5.6 20:43 88% 3 8 0.14:37 83% 4 10.2 11:26 80% 5 11.8 09:51 74% 6 13.5 08:38 71% 7 15.0 07:46 67% 8 16.2 07:11 64% I'm quite pleased with the efficiency figures, since I've got eight cores sharing a single memory controller, even if it is a two-channel DDR4-2133 memory controller For comparison, on an i7/4790K with dual-channel DDR3-1866 Code: 1 4.7 24:44 (100) 2 7.8 14:52 83% 3 10.4 11:12 74% 4 11.9 09:47 63% Code: for u in 1 2 3 4; do taskset -c 1-$u /home/nfsworld/msieve-svn/trunk/msieve -v -ncr -t$u & p=$!; sleep 600; kill$p; sleep 20; done
 2015-06-14, 09:49 #66 pinhodecarlos     "Carlos Pinho" Oct 2011 Milton Keynes, UK 3×1,663 Posts How did you calculate the efficiency? (edit: got your numbers, you determine it proportional to 1 core running ) Do you have an energy meter? Will the consumption be linear as you increase the number of cores? I don't think so.... Last fiddled with by pinhodecarlos on 2015-06-14 at 10:00

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