My Computer's Temperature won't go lower?

[Dartz1]

For quite sometime, my pc's normal temperature won't go lower than 70 degree Celcius. i've done thermal paste process several times but won't work.
please tell me what can i do now.
my games work slower than before.
PLEASE TELL ME WHAT TO DO NOW?
i want to play my games at original speed

my pc specs:
--------------
Intel Pentium D @ 2.66Ghz (2cpu's)
2GB DDR2 RAM
ATI RADEON HD 3450 @ 1GB
ASUS p5kpl am/ps motherboard
80GB sata HDD
LG Cabinet
DVD RW multi

 

[Remeniz]

Open up the Windows Task Manager, click on the Processes tab. Then double click CPU.

Tell us what your CPU usages are here.

 

[Dartz1]

CPU Usage : 10-20% when computer is at rest
PF Usage : 560 to 600 MB when computer is at rest

 

[setishock]

CPU usage at idle is irrelevant here. The temps not dropping down below 70C (158F) is an indication of either the thermal paste is on too heavy or bad airflow through the case. Or both.
Can you post a link to the case you're using?

 

[foothead]

10-20%?! what background processes are there? Sounds to me like you have a virus, which is killing your game performance.

Run malwarebytes anti-malware.

 

[Dartz1]

i have formatted my computer yesterday and installed latest original AVG Internet Security fully Updated
so how can my computer caught by a virus?
and about background process , do i have to post each and every background process's name or there quantity??

 

[Remeniz]

...do i have to post each and every background process's name or there quantity??

Na just watch the Processes and see what's using 10%-20% of your resources. Double click on the CPU header and the process using the most resource will appear at the top.

What temperature monitoring application are you using?

 

[Dartz1]

Its "System Idle Process" using 45-50% of CPU Usage
and i am using Speed Fan 4.40 to Track Temperature.

 

[setishock]

Speedfan is too vauge. You have to set it up to what winbond chip model you have on your motherboard. If not set up correctly it will feed you bogus BS. Get hwmonitor here > http://www.cpuid.com/hwmonitor.php
Next how many programs are running in the tray by the clock?

 

[Remeniz]

Its "System Idle Process" using 45-50% of CPU Usage
and i am using Speed Fan 4.40 to Track Temperature.

Go with what setishock said.

But for your system to be idling at 50% means another process/s is using half your resources while your doing nothing with your computer.

What is process is using the other 50%?