CPU running continuously at 90% on one core

I have Windows 7 home premium running on an AMD X6-1055 6 core processor.
If I start Windows and leave it doing nothing except the background
processes loaded at boot time the CPU runs continuously at 14/15%.

When I inspect task manager it tells me system idle process is 99%, and none
of the 80 running processes register above 0%, but at the bottom CPU use is
still 14%+.

When I look at the performance tab one processor (always the same one) is
running at 85-90% and the others near zero.

When I use a motherboard utility it shows the same thing - one processor at
85%+ and the others near zero.

How do I find out what is running to cause this when task manager does not
show the process? I have run Malwarebytes - it shows nothing unpleasant on
the computer.

In article <>,
says...
>
> I have Windows 7 home premium running on an AMD X6-1055 6 core processor.
> If I start Windows and leave it doing nothing except the background
> processes loaded at boot time the CPU runs continuously at 14/15%.
>
> When I inspect task manager it tells me system idle process is 99%, and none
> of the 80 running processes register above 0%, but at the bottom CPU use is
> still 14%+.
>
> When I look at the performance tab one processor (always the same one) is
> running at 85-90% and the others near zero.
>
> When I use a motherboard utility it shows the same thing - one processor at
> 85%+ and the others near zero.
>
> How do I find out what is running to cause this when task manager does not
> show the process? I have run Malwarebytes - it shows nothing unpleasant on
> the computer.

Try to run Process Explorer by Sysinternals (now Microsoft),
as elevated admin. I guess Win Task Manager need not to show all,
PE may show more processes.

http://technet.microsoft.com/en-us/s.../bb896653.aspx

--
Poutnik
The best depends on how the best is defined.

"Lorne" <> wrote in message
news:...
> I have Windows 7 home premium running on an AMD X6-1055 6 core processor.
> If I start Windows and leave it doing nothing except the background
> processes loaded at boot time the CPU runs continuously at 14/15%.
>
> When I inspect task manager it tells me system idle process is 99%, and
> none of the 80 running processes register above 0%, but at the bottom CPU
> use is still 14%+.
>
> When I look at the performance tab one processor (always the same one) is
> running at 85-90% and the others near zero.
>
> When I use a motherboard utility it shows the same thing - one processor
> at 85%+ and the others near zero.
>
> How do I find out what is running to cause this when task manager does not
> show the process? I have run Malwarebytes - it shows nothing unpleasant
> on the computer.

I made some progress. I found windows system monitor and it shows me that
the cpu usage is caused by system interrupts. What I now need is to work
out which interrupt is causing the problem. any idea how to do that?

"Lorne" <> wrote in message
news:##...
> "Lorne" <> wrote in message
> news:...
>> I have Windows 7 home premium running on an AMD X6-1055 6 core processor.
>> If I start Windows and leave it doing nothing except the background
>> processes loaded at boot time the CPU runs continuously at 14/15%.
>>
>> When I inspect task manager it tells me system idle process is 99%, and
>> none of the 80 running processes register above 0%, but at the bottom CPU
>> use is still 14%+.
>>
>> When I look at the performance tab one processor (always the same one) is
>> running at 85-90% and the others near zero.
>>
>> When I use a motherboard utility it shows the same thing - one processor
>> at 85%+ and the others near zero.
>>
>> How do I find out what is running to cause this when task manager does
>> not show the process? I have run Malwarebytes - it shows nothing
>> unpleasant on the computer.
>
> I made some progress. I found windows system monitor and it shows me that
> the cpu usage is caused by system interrupts. What I now need is to work
> out which interrupt is causing the problem. any idea how to do that?

An interesting additional effect is that if I put the computer into sleep
mode and wake it up the problem disappears - cpu down to 1 or 2% and use of
cpu by interrupts under effectively zero.

Does anybody have detailed knowledge of what sleep mode actually does that
may change the behavior of interrupts?

If anybody else has this problem the procedure to find a solution is here:
http://www.msfn.org/board/topic/1402...dpc-interrupt/

It requires some reasonable understanding of computers to follow it however.
In my case it was a driver called nmserial.sys that was hogging the cpu.

************************************************** ************************

"Lorne" <> wrote in message
news:...
> I have Windows 7 home premium running on an AMD X6-1055 6 core processor.
> If I start Windows and leave it doing nothing except the background
> processes loaded at boot time the CPU runs continuously at 14/15%.
>
> When I inspect task manager it tells me system idle process is 99%, and
> none of the 80 running processes register above 0%, but at the bottom CPU
> use is still 14%+.
>
> When I look at the performance tab one processor (always the same one) is
> running at 85-90% and the others near zero.
>
> When I use a motherboard utility it shows the same thing - one processor
> at 85%+ and the others near zero.
>
> How do I find out what is running to cause this when task manager does not
> show the process? I have run Malwarebytes - it shows nothing unpleasant
> on the computer.

Sleep will shut down power to USB ports if device is marked to conserve
power. When you SLEEP you may be depowering some USB device that is
interrupting the system trying to initialize after a full power up.

Guessing here, but .......

"Lorne" <> wrote in message
news:Okb#...
> "Lorne" <> wrote in message
> news:##...
>> "Lorne" <> wrote in message
>> news:...
>>> I have Windows 7 home premium running on an AMD X6-1055 6 core
>>> processor. If I start Windows and leave it doing nothing except the
>>> background processes loaded at boot time the CPU runs continuously at
>>> 14/15%.
>>>
>>> When I inspect task manager it tells me system idle process is 99%, and
>>> none of the 80 running processes register above 0%, but at the bottom
>>> CPU use is still 14%+.
>>>
>>> When I look at the performance tab one processor (always the same one)
>>> is running at 85-90% and the others near zero.
>>>
>>> When I use a motherboard utility it shows the same thing - one processor
>>> at 85%+ and the others near zero.
>>>
>>> How do I find out what is running to cause this when task manager does
>>> not show the process? I have run Malwarebytes - it shows nothing
>>> unpleasant on the computer.
>>
>> I made some progress. I found windows system monitor and it shows me
>> that the cpu usage is caused by system interrupts. What I now need is to
>> work out which interrupt is causing the problem. any idea how to do
>> that?
>
> An interesting additional effect is that if I put the computer into sleep
> mode and wake it up the problem disappears - cpu down to 1 or 2% and use
> of cpu by interrupts under effectively zero.
>
> Does anybody have detailed knowledge of what sleep mode actually does
> that may change the behavior of interrupts?
>
>