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Old 2015-05-07, 20:15   #56
chalsall
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"Chris Halsall"
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Quote:
Originally Posted by xilman View Post
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.)
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Old 2015-05-15, 17:20   #57
Xyzzy
 
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http://arstechnica.com/gadgets/2015/...-mini-desktop/
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Old 2015-06-09, 21:07   #58
fivemack
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Default 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
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Old 2015-06-09, 21:36   #59
fivemack
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Default 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.
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Old 2015-06-09, 22:03   #60
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I realize that you are in the UK, but perhaps you could use this site to track down models to look for.
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Old 2015-06-10, 03:09   #61
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Quote:
Originally Posted by fivemack View Post
I have a Xeon D-1540 machine now.
Wow! You have a freaking big foot!
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Old 2015-06-10, 20:33   #62
fivemack
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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.
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Old 2015-06-11, 15:30   #63
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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).
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Old 2015-06-12, 00:21   #64
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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
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Old 2015-06-14, 09:24   #65
fivemack
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Default 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
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Old 2015-06-14, 09:49   #66
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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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