Hyperthreading hurts 5.3?

Anthony Atkielski atkielski.anthony at wanadoo.fr
Wed Jan 12 20:42:51 PST 2005

Subhro writes:

S> This *used* to be true. I am using a AMD64 3000+ and the idle
S> temperature is 28C. The room temp is around 12-14C. After asking this
S> kid to crunch FPs for over 16 hrs, the processor temperature rose to
S> only 38C. I am not using any special cooling gears, just the stock
S> heatsink fan combo that came with the box pack.

The case temperature on my FreeBSD server runs at about 36° C with a
room temperature of 25° C, and the 3.0 GHz Intel P4 processor is at
about 44° and very nearly idle (0.5% busy). After running the processor
at 100% for a few minutes, it gets up to 51° (I haven't tried the
experiment beyond that, and the system is never 100% under normal
conditions). There are seven fans (I'm not taking any chances): two that
blow into the case over the disk drives, one that blows down onto the
motherboard (directly over the CPU), and three that blow through and out
of the power supply--plus the P4 CPU fan. They draw air through filters
so they don't create that much movement, but I like the redundancy.

My desktop running WinXP has an AMD Athlon 1800-something.  The
processor runs at about 59° and the case is at 29°; this case has only
three fans, one in the PS, on inward fan on the case, and a tiny CPU fan
over the processor.  The arrangement of the MB is such that the CPU
doesn't have a very clear airflow over it.  The CPU fan has been
replaced twice, as the first fans were sleeve bearings that failed
almost immediately (I installed my own ball-bearing fan after that).
The case fan was my own addition.  On one occasion the CPU froze after
the fan failed, but it did not seem to break.  I don't know if this
model of processor includes any protections.

It would be nice if someone would design processors that did not require
active cooling, as the need for a CPU fan to keep the system from
self-destructing is a major weak point for the hardware.

Thank goodness modern operating systems idle the processor when it's not
in use.  I shudder to think what it would be like under old versions of
Windows (including Win9x) that just looped when idle.  FreeBSD runs cool
as a cucumber, even though it handles all my Web and mail and DNS and
NTP traffic.

Which reminds me: I'm still looking for a way to monitor system
temperature at securelevel=3 on my FreeBSD system, so suggestions are
welcome.  Healthd is fine but it won't work at securelevel=3.


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