test RAM,the CPU usage was 100% in WinXP 64bit

[karry]

Dear Sir,
I use Passmark burn-in v7.0 build 1015 test RAM,the CPU usage was 100%.If the COM Port and RAM at the same time test,the com port test fail(OverRun) at once.Pls also help to have a look the issue?
CPU:I7-3555LE PCH:QM77 RAM:Apacer DDR3 1600MHZ 8GB
OS:WinXP Professional Englsih 64bit with SP1
Thanks

[David (PassMark)]

COM port errors are to be expected when the system is under very high load.
On the other hand these errors should disappear if the CPU has time to service the COM port.

[karry]

I know.But why the CPU loading will very high when after test the RAM?
If I don't test RAM,the loading is small.
If COM and RAM were tested together, so COM cannot test the maximum baud rate in WinXP 64bit system.
Pls help to answer why?
Thanks

[David (PassMark)]

The CPU is used as part of the RAM test.

[karry]

The CPU loading was 60%~70% under other OS,only unoder WinXP 64bit OS the CPU loading 100%.
Why the CPU loading very high use passmark test RAM under Winxp 64bit OS?(The RAM duty cycles set 100%)
the OS issue? or Software issue?

[karry]

The CPU is used as part of the RAM test.

Please help me to see the software whether the existence of such problems? tks