CPU temp's on core 2 duo, should they be significantly different?

[Gonzalo Nemmi]

On Monday 23 June 2008 16:06:20 George Hartzell wrote:
> DA Forsyth recently mentioned the coretemp driver, which fetches the
> core temperatures for Core 2 Duo chips.
>
> I'm in the middle of building up a Shuttle SG31G2 (7-STABLE) and
> loaded the driver to see what it told me.
>
> I've noticed that cpu.0 is consistently hotter than cpu.1, even on an
> unloaded machine.  Is that because that core's doing housekeeping work
> whilst the other is truly idle?
>
> dev.cpu.0.temperature: 44
> dev.cpu.1.temperature: 29
>
> If I background a pair of "dd if=/dev/urandom of=/dev/null" so that
> the cpu's are busy, both go up but cpu.0 stays hotter.
>
> I'm asking because I'm worried that this could be a sign that I didn't
> get the heatsink goop spread out sufficiently well....
>
> Thanks,
>
> g.

For what is worth .. my readings:

root at inferna:~ # kldload coretemp
root at inferna:~ # sysctl kern.version
kern.version: FreeBSD 7.0-RELEASE #0: Sun Feb 24 19:59:52 UTC 2008
    root at logan.cse.buffalo.edu:/usr/obj/usr/src/sys/GENERIC

root at inferna:~ # sysctl hw.model
hw.model: Intel(R) Core(TM)2 Duo CPU     E4500  @ 2.20GHz
root at inferna:~ # sysctl dev.cpu.0.temperature; sysctl dev.cpu.1.temperature; 
date "+%H:%M:%S"
dev.cpu.0.temperature: 25
dev.cpu.1.temperature: 24
00:08:29
root at inferna:~ # dd if=/dev/urandom of=/dev/null &
[1] 5482
root at inferna:~ # date "+%H:%M:%S"
00:08:48
root at inferna:~ # sysctl dev.cpu.0.temperature; sysctl dev.cpu.1.temperature; 
date "+%H:%M:%S"
dev.cpu.0.temperature: 36
dev.cpu.1.temperature: 36
00:10:39
root at inferna:~ # j
[1]  +  5482 Running                       dd if=/dev/urandom of=/dev/null
root at inferna:~ # date "+%H:%M:%S"
00:11:13
root at inferna:~ # sysctl dev.cpu.0.temperature; sysctl dev.cpu.1.temperature; 
date "+%H:%M:%S"
dev.cpu.0.temperature: 40
dev.cpu.1.temperature: 37
00:11:38
root at inferna:~ # sysctl dev.cpu.1.temperature ; sysctl dev.cpu.1.temperature ; 
date "+%H:%M:%S"
dev.cpu.1.temperature: 35
dev.cpu.1.temperature: 35
00:13:58
root at inferna:~ # j; date "+%H:%M:%S"
[1]  +  5482 Running                       dd if=/dev/urandom of=/dev/null
00:14:20
root at inferna:~ # sysctl dev.cpu.1.temperature ; sysctl dev.cpu.1.temperature ; 
date "+%H:%M:%S"
dev.cpu.1.temperature: 39
dev.cpu.1.temperature: 39
00:14:30
root at inferna:~ # sysctl dev.cpu.1.temperature ; sysctl dev.cpu.1.temperature ; 
date "+%H:%M:%S"
dev.cpu.1.temperature: 37
dev.cpu.1.temperature: 37
00:14:57
root at inferna:~ # fg
dd if=/dev/urandom of=/dev/null
^C29752816+0 records in
29752816+0 records out
15233441792 bytes transferred in 378.928688 secs (40201342 bytes/sec)
root at inferna:~ # 

Hope it helped :)
-- 
Blessings
Gonzalo Nemmi