At full speed, you should not go over about 50'C and you shouldn't get a
BSOD. Something is wrong with the setup or the cooling.
Normal idle temps for an x2 should be around 30-35'C in a room with
ambient temperature of 20'C and proper case & CPU cooling.
Perhaps your heatsink is not properly seated?
Or your case has very inadequate fan exhaust and you have a big hotspot
inside the case?
A friend once had a heat problem with his system. It turned out the
power supply fan was thermal controlled and would run at very slow
speeds if the power supply wasn't being taxed.
The ambient case temp was over 40'C so the heatsink could not cool the
CPU enough under load. He didn't have a case fan, just the single power
supply fan, so the case had poor air flow. There were mounting holes for
a case fan, so I just added a $15 80mm fan to exhaust the hot air and
all was well again.
But that's running at half speed again, so you're losing performance and
not using the second core. Double whammy!
Note, the test program may be single threaded. The OS will then dump
the various sundry windows processes onto the other core as
it likes but likely those processes still won't work that one
out much compared to the load prog. which is made by design to use lots of
cpu.
That's not completely accurate.
Even with a single threaded app, Windows XP will distribute the process
across the two cores, and it's rarely a 50/50 split. What actually
happens is the thread is distributed as the process priority is
executed, so the load will vary on each core as the program runs and
time slices with the other processes that are running at the same time.
Sometimes when you upgrade a processor, XP doesn't upgrade it's kernel
hardware access layer (HAL) to work with the extra core - it doesn't
"see" your dual-core CPU. There are two kernels, one is the single
processor (SP) and the other is the multiple processor (MP) HAL.
Also, you need to ensure your BIOS supports dual-core processors, and
that if you're running XP Home Edition, you have service pack 2 (SP2)
installed.
Now to check, bring up the Task Manager. Look under the Performance tab
and if it only shows one graph for your CPU then XP is not running the
multiple processor HAL kernel and it's not using the second core.
You can also check in Device Manager where it should be showing 2
processors. Expand the Computer options and you should see "APCI
multiprocessor PC" for the MP HAL.
If it says "Advanced Configuration and Power Interface(ACPI) PC", then
you're still running the SP HAL.
So if it looks like you're using just one core, you need to open the
Device Manager and uninstall the CPU from the system, and restart your
computer. That should force XP to update the HAL and you should have two
CPUs shown in Device Manager after the restart. You may have to remove
the CPU running in Safe Mode...I can't remember if it'll work from the
normal desktop mode.