2nd CPU Temperatures in T7810

Hey Gang, Love the forum here.  Lots of good stuff learned from you in my Precision T7810 build ventures.  I recently added the 2nd processor (Xeon E5-2680 V4) with the OEM 2nd heatsink with Arctic MX4 thermal compound and have some concern for the CPU temperatures.  I'm hoping for some feedback from those with a 2nd CPU on the T7810.

I'm using HWiNFO64 v6.42-4360 for my temperature data.

2nd CPU "CPU Package" is registering 66°C at near-idle (typing this post) but at 40% overall computer load per Windows Task Manger during my typical usage, the CPU reaches 84°C.  At 100% computer load the 2nd CPU seems to stabilize at 86°C with the fans kicking up when the temp goes above 86°C.  The room temperature is about 24°C (73°F).  CPU0 is consistently 15°C lower with the cooler air.  

These are 120W TDP processors with a Tcase rating 86°C.  My first question, am I looking at the correct HWiNFO metric?  And secondly, should I be concerned about the temps?  I think these server-grade Xeons are pretty temperature tolerant but I seem to be right at the limit and don't want to damage them.

Another curiosity while I have your ear.  HWiNFO displays "CPU Package Power".  Even at 100% computer load this value doesn't go much higher than 99Watts which is different than Intel's performance spec of 120Watts.  

Any insight on all of this?  Many thanks!

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  • Maximum operating temperature  is: 86°C
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  • The fan curve sucks in the Dell. Go into your bios settings and set the fan where you can stand it. I do about 30 percent. It doesn't keep it at 30 but it makes the curve start at 30. That will help keep everything much cooler. However when you do load the system up don't expect to hear the fans ramp up until your close to 80c on the cpu. I have not found a way to change this as I'd like the fans to be full tilt at 70.

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  • I haven't tried to adjust the bios fan settings and record temperatures but I found that HWiNFO has a convenient feature with bidirectional control of the fan speeds where if I bring the fans to maximum speed under full computer load then the 2nd CPU Package temps drop to about 53°C.  Wow, talk about the noise too.   This proves the T7810 has plenty of cooling headroom for this and probably more power-hungry CPU SKUs but also that the Dell A34 bios fan curve can holding CPU temps within the limits of Intel's specification for these processors.  A this point, I just don't know if running at a perpetual 86°C is a good idea.   

    That said, I think it would be nice have some more control over the individual fans in bios rather than a single setting for the set.  That way one could bump the 2nd CPU fan up say 15% and not pay much of a noise penalty.

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      • Rob Frank
      • Rob_Frank
      • 3 mths ago
      • Reported - view

      Smithy if you care I'm in the process of swapping over to a supermicro 4u heatsink. I'm using one of the case fans which is a 92x38mm fan. I just modified the bracket for it at work but I'll get some pics up as soon as it's done. I'm doing this in a t5810 but as far as keeping your second cpu cool having the hot air from the first cpu getting piped into it this could be a solution.

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  • Rob Frank Good idea.  Also, I found an unused fan header connection on my motherboard.  This one appears to be for a hard drive when installed in the 5.25" bay.  I haven't determined the feasibility or performance of this but I'm wondering if a custom shroud could divert some of the CPU-0 exhaust around CPU-1 and using the extra fan connection, supply CPU-1 with some fresh air from around CPU-0. 

    Dell incorporated a small offset between the processors which surely helps but unfortunately, there isn't much room between the processors to to accommodate such a shroud.  Any diverters would probably help keep things cooler under the stock fan settings but would reduce the cooling effectiveness under the extreme conditions when the air volume moved by the fans would be restricted by the diverters.  I think I might look into the fan module that is integrated into the 2nd CPU heatsink.  I don't know much about fans  or how the fan controller works but if it is a standard size fan then its possible I could find something that flows a little better volt/volt than the stock unit.  This might balance out the temps a little more.  

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  • The hdd fan header I am going to use for an exhaust fan at the rear of the pc. I'm just repurposing the fan that was included with the supermicro heatsink. The stock Dell coolers use 80mm fans. I have one of the 7810 2nd cpu coolers and it's actually a very nice cooler with a decent fan already but what I'm doing with the 4u cooler trump's that by alot. 

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  • Here it is. Test fit anyways. Had to drill out the holes in the adapter plate to fit the longer Dell shouldered screws. Letter G drill bit and the metal is hardened so have fun. Since the plate is thinner than the aluminum that the Dell heatsink uses I had to add 2 washers to the spring. I also took a vrm heatsink from an old ibm server I had and modified it to go onto my vrm with a 1.5mm thermal pad and spring pins. Looks like I am going to have to modify the ducting for the dimms because the new cooler hits it. This is also a picture of the larger case fan mounted onto the cpu heatsink.  The screws in the 7810 heatsink are bigger than the ones on my 5810. I can't see drilling the holes bigger because of lack of material. And the easiest way to get the screws I have is to buy a used 3610 or 5810 heatsink.

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  • Nice.  You mentioned the bigger fan but I didn't ask about the specific design advantages of the 4u cooler. Clearly I can see it has 5 heat pipes vs. 4 on the Dell coolers.  What is the axial length of that cooler/fan combo? Second question, do you know what the power limit is of that HDD fan header? I think the HDD fan option for these Dell are close to 30mm.  Just big enough to keep the air from stagnating around the hdd stuffed into that corner of the box.  I'm wondering if there is any issue running a bigger fan on that circuit.

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      • Rob Frank
      • Rob_Frank
      • 3 mths ago
      • Reported - view

      Smithy I'll measure the heatsink fan combo tonight when I'm home. As far as the hdd header goes I have no clue. I did connect the supermicro 92mm fan to it and it's rated at .36 amps. Had no problem passing epsa test. And my 1.5amp system fan plugged into the cpu header also had no issue.

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  • Full assembly is 117mm long.

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