Greg, Again, thank you for the well thought out answers and analysis.
I downloaded CoreTemp this evening and it is giving approximately the same temps. Not sure on the fans. They are the stock fans that come with the Swiftech kit. I backed off the oc frequency to 120 (a 2.5 GHz value) and backed off the cpu voltage to 1.2V from the default 1.225 V. I made no other changes for the original overclock in the BIOS. These changes resulted in little or no change. As the CPU throttles itself back due to inactivity (currently running at 1.8 GHz), I see no change in the temperatures. After changing to the Arctic Silver 5, the temps are currently running 39 to 43 for the four cores at idle. If I run the Prime95 torture test, the temp rises almost immediately to 60 to 64 degrees C. (This is with no overclocking, running at 2.5 GHz). After 3 minutes, 64 to 66 degrees C. After 10 minutes, the temps are still 64 to 66 degrees. After 20 minutes, a slight change to 65 to 67 degrees C (although the high and low fluctuate up and down over time). Raising the clock back to 150 (a 3.0 GHz cpu speed) resulted in the temps raising to 71-74 degrees C. Halting Prime95 drops the temps to 42-45 almost immediately. After 5 minutes, the temps are back to 38-43 degrees C. Backing the oc back to 120 (2.5 GHz) leaves the temps at 38-42 degrees C. What does it mean that the temps rise fast to a max and fall fast to a min? There is little upward or downward trend between idle and 100% usage with time. I could try the thermometer in the reservoir, although it would require some dis-assembly and acrobatic maneuvers. :) I find it strange that the idle temps seem unchanged between the overclock and the underclock situations. Also, the maximum temps reached are lower this evening (which could be related to cooler ambient temperatures) after changing the TMI, but the idle temps have actually raised even with the underclocking/undervolting. I have been searching google about this problem/situation and see a wide variety of temperature claims for the i7 920. Some claim almost ambient temperatures at idle and 50-60 degrees C at 100%. Others seem closer to my results with 35-45 degrees C at idle and 70-80 degrees at 100% usage. These result are usually on air cooling. Thanks for the guidance. Jim > -----Original Message----- > From: [email protected] [mailto:hardware- > [email protected]] On Behalf Of Greg Sevart > Sent: Saturday, July 09, 2011 10:02 PM > To: [email protected] > Subject: Re: [H] Water Cooling and ambient temperature > > It's certainly possible. I'm a fan of CoreTemp myself, but Realtemp is also > popular. Make sure that you're running the latest versions, too, since they > could be using faulty Tjmax data. The DTS (digital thermal sensor) on these > chips does not report the actual temp--they report the margin between the > current temp and the pre-defined Tjmax temperature. Therefore, if the > utility is using an incorrect value for Tjmax, the reported temp will be wrong. > > Replacing the TIM isn't going to make but a few C difference probably, and > it'd be more pronounced at load. > > What fans are you using on the radiator? A lot of fans don't create much > static pressure, which is required to move air through the restrictive radiator. > I'm using 3x Scythe SFF21F fans on mine that seem to do a decent job. They > don't have the greatest static pressure spec either, but they're extremely > reliable and are fairly quiet. I've had the same fans on the radiator for 4 > years... > > I'd also try backing everything to stock frequencies and volts. I think you > indicated a very mild overclock, but some boards can take great liberties with > vcore and such when left on automatic, so you could be dumping more heat > than you realize. These i7-9xx series chips are rated for a 130W TDP, but it > isn't that hard to get another 60, 80, 100, or even more watts with big > overclocks and/or big voltage bumps--some of which may very well be > inadvertent. > > When you apply a load like LinX/IBT or Prime95 small FFT, does the temp > jump up quickly and increase only slightly (a few C), or does it jump quickly > and then continue to rise? Is there any way that you could get a temperature > reading of the water itself--like a temp probe on the radiator inlet? > > Do you have any of the power management processor features disabled in > the system BIOS? Most overclocking guides say to disable most of them, but I > refuse to. I personally don't consider it a stable overclock if I have to disable > features. Things like C1E, EIST, etc. can play a big role in idle temps. > > Finally, some chips just have bad thermal sensors and can be off by a good > margin. They aren't engineered to be exact--they're engineered to be an > input into the thermal management system. It could also be that my 970 is > reading low (and the 32nm process shrink probably means that it's pulling > less at idle, too). I just don't remember what my idle temps were on the 930 > and 960 that proceeded it. My load temps were close to yours, but that was > with a big overclock (4.0-4.1GHz) with a healthy voltage bump. > > > -----Original Message----- > > From: [email protected] [mailto:hardware- > > [email protected]] On Behalf Of James Maki > > Sent: Saturday, July 09, 2011 10:43 PM > > To: [email protected] > > Subject: Re: [H] Water Cooling and ambient temperature > > > > Could the temperature monitors I am using be wrong? > > > > > -----Original Message----- > > > From: [email protected] [mailto:hardware- > > > [email protected]] On Behalf Of James Maki > > > Sent: Saturday, July 09, 2011 8:33 PM > > > To: [email protected] > > > Subject: Re: [H] Water Cooling and ambient temperature > > > > > > Well, I took the cpu block off. Cleaned it off (I may have applied > > > too > > much > > > TIM the first time.) and reapplied less. I only have the Arctic > > > Silver 5 > > at this > > > time. Reassembled and was seeing almost identical temps. Took the > > > block > > off > > > again. Definitely did not have too much TMI this time. Cleaned off > > > and reapplied again. Reassembled only to see similar temps again. > > > The pump > is > > > working, so that is not the problem. Any other suggestions? Seems > > > like a simple system that should just work. Can the block be defective? > > > > > > Thanks for any insight. > > > > > > Jim >
