CPU usage jumping while running small programs

[cjf1023]

Hello,
I just recently installed a new CPU/MB/HD in my computer and am having a small problem.

When I run programs, like steam, it brings my CPU usage to between 5%-20% randomly. I compared it to my friends computer running the same process and his was a steady 1%. It doesn't effect anything in terms of performance but it's quite bothersome to watch it jump around like that. Any clues to what the problem might be?

Some numbers from Windows Resource Monitor:

Steam.exe (not downloading anything) 1.97
System Interrupts (not sure what this is) 1.20
Firefox.exe (.54)

Using a
Intel Core i5-2500K Sandy Bridge 3.3GHz

Here is a screenshot of Resource Monitor for ease
http://imgur.com/Wubte

If anyone has any suggestions as to why this is happening would be greatly appreciated. Thanks!

 

[alyoshka]

Configuration of earlier rig and the new rig please.

 

[cjf1023]

Unfortunately I don't remember exactly what the CPU/Mobo was in my old configuration, but now it consists of:
-ASRock Z68 Extreme3 Gen3 LGA 1155 Intel Z68 HDMI SATA 6Gb/s USB 3.0 ATX Intel Motherboard
-Intel Core i5-2500K Sandy Bridge 3.3GHz (3.7GHz Turbo Boost) LGA 1155 95W Quad-Core Desktop Processor Intel HD Graphics 3000 BX80623I52500K
-Western Digital Caviar Black WD1001FALS 1TB 7200 RPM 32MB Cache SATA 3.0Gb/s 3.5" Internal Hard Drive -Bare Drive
-Nvidia GeForce GTX 460

The only thing that wasnt changed with the swap was the graphics card and the PSU (550W Antec)

EDIT**
As of this morning, it is jumping between 60% and 90% with just Firefox open. Says firefox is taking up an average of 50% CPU usage. Doesn't make sense

 

[alyoshka]

Try disabling hardware acceleration in firefox. and then see if the CPU spikes still happen.