cancel
Showing results for 
Search instead for 
Did you mean: 

CPU PLL OC - False Temperature readings?

redone13
Level 7
Hello,

I have a question regarding CPU PLL OC and temperatures. I have a 5.1GHz OC on a my 7700K using a Maximus IX Hero. I have noticed that many people say the default CPU PLL OC is around 1.2v with some saying that overvolting and undervolting this value can skew the DTS and give inaccurate readings. Regardless, the range appears to be 1.1 to 1.3v which is much different than the Auto value the M9H uses (Also looks like Apex behaves the same).

The issue that arises from this is that the M9H by default makes the CPU PLL OC voltage .592. In the BIOS, this setting is called CPU PLL Bandwidth and there are 8 values, 0-8. The BIOS itself recommends 6-8 for higher OCs, however, if I change the voltage from 0 or Auto (both give the .592v value) to just level 1(.696v), my temperatures shoot up from 75 degrees celsius load in x264/Realbench to about 85 degrees.

Level 2 PLL Bandwidth is .696v, Level 3 equals 1.0v, level 4 equals 1.15 and higher like level 6 is in the neighborhood of 1.4. All these values produce a drastic increase in temps much the same way going from Level 0 or Auto to level 1 does (I didn't test 1.4 as it is rather high).

The question at hand is, is leaving it at Auto or .592 (out of Intel spec btw) masking or under-reporting the real temperatures as evidenced by the 10 degree temperature increase going from just level 0 to level 1?

It makes sense that there is an increase of ten plus degrees going from .592 to 1.15, however, it does not make sense when it occurs going from .592 (level 0 or Auto) to just one notch higher .696 (level 1) of CPU PLL Bandwidth. It leads me to believe there is an inaccuracy in the default setting which, like mentioned earlier, is much different in comparison to Intel's spec as well as other motherboard manufacturers' spec (MSI and ASRock from what I've read).

FYI, I am using HWinfo to monitor my voltages and temps on a NH-D15. I've disabled core temps in HWinfo so that Realtemp can monitor them. They all seem to be in accordance. Thanks.
7,012 Views
3 REPLIES 3

schoolofmonkey
Level 7
Are you still trying to find the answer, for OC.net 😄

Couldn't hurt hearing it from the source of the board itself. It is very curious to me the temperature increase going from level 0 to level 1 PLL Bandwidth. I do understand there is a difference between CPU PLL and PLL OC but if the board recommends using level 6-8 for high frequency OCs, which puts it at a similar PLL OC as other board manufacturers default value and closer to Intel spec, why isn't it used in the first place? It was originally observed that undervolting CPU PLL could skew DTS readings and I would like to know if this extends to PLL OC as well because that default value on these boards seems undervolted by default on Auto. Any clarification would be appreciated. Thanks.

sdmf74
Level 11
And again this is why I hate that asus uses "auto" for most settings in bios, Auto can and usually does mean just about anything.

I too really would like some feedback on the PLL bandwidth / cpu PLL setting. I just recently changed my cpu block from swiftech apogee xl (terrible restrictiveness) to the new
Bitspower summit EF-X rgb (so I could use it with aura & motherboard rgb header) and I took extensive temp readings with both. Well for the past week I have been wondering why Im getting cpu temp spikes with the bitspower sometimes 10+ degrees over what I was getting with the swiftech! Even when idle at desktop/surfing the web. This shouldnt be the case cause I know the bitspower not only is less restrictive but should produce lower temps.

I have been wondering if I used too much T paste or if my mount was funky etc. and It just dawned on me that I changed the PLL bandwidth from auto to 6! (which is what the bios recommneds). I obviously meant to keep all the settings the same to compare the performance of both cpu blocks but for some reason I changed the settting anyway and forgot about it. I had no idea it would affect temps so much or at all for that matter. I wonder if these are accurate readings or as you said if the setting is skewing the readings/accuracy.

At least I can go back and do a legitimate comparison now....
ASUS Maximus 13 Hero, Intel I9 11900k, EVGA GeForce RTX 3080 FTW3 ULTRA