15 to 20 degrees difference between E8400 cores normal?

[broona]

My E8400 idles at approximately 30 degrees on one core, and 40 degrees on the other, and under load, the differences increase up to 20 degrees!

Is this normal, or do I need to try reseating my HSF? I have noticed that the motherboard appears to have 'flexed' a little at the edge nearest the HSF, as my Scythe Ninja cooler hasn't got a backplate to support it, could this be part of the problem, and if so, does anyone know of a way to retrofit a backplate? Cheers.

 

[Defiance_co]

Hiya,
I personally would say redo seating or even lapping comes to mind, i have never found a hsf/waterblock that didn't benefit from lapping to some degree, even doing this alone and not the cpu you should find a benefit for sure

The flexing i've found for the last few cpu generations is normal, it's to do with the specified force required by amd/intel to securely attach for use (more force equals better thermal conductivity etc)

I've still found some flexing with backplates for water blocks, not as much as a oem hsf but there is some, don't think you'd never get flex especially with the weight and size of modern hsf's lol

I'm sure my bro has the same cpu and similar cooler and his core temps varied by a few c

Can check the weekend for you if no one jumps in here

 

[MeatLoaf]

Yes its perfectly normal, i think theres a problem with the thermal sensors on the CPUs themselves.

My E8400 had the same issue but worked fine so didnt really bother me.

 

[valdai]

I thought the only issue with the thermal sensors was that they sometimes got stuck? Are they sometimes just plain wrong as well?

 

[PaulyD]

He hasn't stated that they change, I reckon the one at 40c doesn't move

 

[broona]

I have an E8400 in each of my systems, the newer one in my main system (the one I'm talking about in this thread) is lapped and reports temperature changes as it goes, the other older one constantly reads 40 and 41 degrees respectively on the 2 cores.

 

[MeatLoaf]

I thought the only issue with the thermal sensors was that they sometimes got stuck? Are they sometimes just plain wrong as well?

Yes sorry thats waht i meant mine was stuck but it always differes by a fair few degrees from one core to the next

 

[pieman109]

My old E8400 had about the same temp difference between the cores, worked perfectly though and appears that loads of pll have the same situation. I'm going to be installing another e8400 shortly and I'm expecting exactly the same thing meself. As long as it works and overall temps don't go through the roof, I wouldn't worry about it.

 

[phytal]

try recoating the cpu with a good TIM

 

[broona]

try recoating the cpu with a good TIM

I always use AS5, so that shouldn't be the problem.

It's working fine at idle and under load, so I'll not worry too much about it, but I might still do a backplate mod just for my own peace of mind.