Dynatron LGA3647 Cooler Options

JSNAS

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Dec 26, 2016
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@JSNAS you need a long T30 bit. I have it installed on a X11SPH in the lab.
Yes, I've ordered the long T30 bit you suggested. But I'm more wondering if the B11 fan bumps into that skinny (non-cpu) heat sink thingy just beyond the CPU socket (towards the back side of the motherboard)? I wasn't quite sure if you had actually installed a B11 on an X11SPH, but sounds like you have, which is awesome. I should be good-to-go. Thanks.
 

JSNAS

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Dec 26, 2016
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I had one more general question: any guess which of these two will cool more efficiently/quietly?

1) SuperMicro 4U SNK-P0070APS4? 4U has 15% larger 92mm fan which is nice, but no copper heat pipes. It also seems to have less overall fins which means less surface area making contact with the air. But the air also has less distance to travel through the fins, so perhaps less work for the fan?

2) Dynatron 3U B11? 3U has 15% smaller 80mm fan but has copper heat pipes which is nice. Also seems to have more overall fins which is good, but longer distance for the fan to push the air all the way through, which might be more effort for the smaller fan?

The only specs I could find were:
- SuperMicro 4U: at 3800 (max) rpm, dBA=38, but no CFM numbers provided. Also no lower fan speed numbers to compare against B11, nor any thermal specs.
- Dynatron 3U B11: at 4000 (max) rpm, dBA=42.2 and CFM=50. At 1300 rpm, dBA=16 and CFM=12.5. They also provide a Thermal Performance Curve which is nice to have (but without comparison data for the SM 4U, not too useful).

Bottom-line: Main plus for the SuperMicro is the 15% bigger fan. But I'm guessing the Dynatron might work just as well or better (even with a smaller fan) due to the copper heat pipes and more surface area on the fins.

Which would you install if you had the space in the chassis for either? Does either manufacturer have a better track record of making quiet/efficient heat sinks? (note that I plan to replace the stock fan with a Noctua regardless of which cooler I go with)
 
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Patrick

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I like the B11. It depends on what CPU you are using though.
 

JSNAS

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Dec 26, 2016
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I have a Silver 85W CPU, but when you say it depends, what do you mean? For what CPU TDPs would you think the 4U might be a better fit? My goal is the quietest build when the CPU is running full speed, regardless of size of the heatsink (since cost difference is minimal between the 3U and 4U).
 

JSNAS

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Dec 26, 2016
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OK, so I went with the B11 (on X11SPH-nCTF MB + 4114 CPU, basically identical build to what Patrick reviewed), but the fan is revving up to max and then back down repeatedly every 15-30 seconds, even during BOOT and/or when IDLE (in FreeNAS). Dumb question: was there any plastic protection that I needed to peel off the heatsink paste before clamping down? I, of course, removed the plastic cover that protected the entire bottom of the heatsink, but I'm wondering if I missed something? But from what I can tell, it definitely seems like the heatsink is correctly stuck to the CPU (ie. I'm at least not able to gently pry it off).

The only other possibility is that it doesn't like the Noctua NF-A8 fan that I swapped in. I didn't actually try the stock fan, because it's fairly complicated to swap the fan on the B11 (you have to use a putty knife to unclip the fan bracket) and I wanted to be sure I could swap to the Noctua before installing the whole thing on the motherboard.

It definitely seems like I'm not getting much/any cooling to the CPU (though I haven't checked CPU temps yet).

Any ideas on why the fan would rev up and down so frequently? Anything else I can try to help diagnose?
 

K D

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Dec 24, 2016
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Looks like an issue with the fan threshold in IPMI. Common issue when using noctua fans with SM boards. The fix has been posted in the forums several times. Search for ipmitool sensor thresh and you should be able to find the right post.
 

JSNAS

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Dec 26, 2016
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Awesome, thanks, @ K D! The link that helped me the most was this resource page:
How To: Change IPMI Sensor Thresholds using ipmitool

For my Noctua NF-A8 attached to the B11, I ended up doing this:
Code:
# ipmitool sensor thresh "FAN1" lower 200 300 400
Now everything is running great and the temps looks fairly reasonable (CPU 25-30C)! (although only minimal testing so far)
 

JSNAS

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Dec 26, 2016
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Patrick (or others): By the way, if I ever decide to swap the B11 heat sink for something else, do you have any tips on how to separate it from the LGA3647 CPU (based on your experience with swapping CPUs for all the Xeon-SP reviews)? When I initially tried separating them yesterday (before K D gave me the ipmi tips), it wouldn't budge at all. Does it have to be heated up or something to loosen the putty? Any special tools I should use to avoid damaging the parts?
 

Patrick

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@JSNAS - TIM breaker and a flat head screwdriver. Slightly warm helps. If you look at the heatsink / clip there is one corner edge that is different from the others. Once you see it, it will make sense.
 

K D

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Dec 24, 2016
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Never had issues in pulling it out when it is warm ( System had been running for a few hoursbefore I had shutdown). Like @Patrick mentioned one side of the clip is slightly different. If you remember how you clipped it ON, you just remove it the other way.

With xeon D systems, I used to run it for a few minutes without any airflow and wait for the paste to heat up before removing the heatsink.