I built a gaming desktop but for some reason my entire system will lag intermittently and has done so since I built it. The mouse will stop moving and the sound will stutter for about a half second at a time, sometimes every few seconds. This appears to disrupt networking as well and will often prevent webpages from loading. The lagging doesn't seem to be associated with the use of any particular system resources.
I've tried the following steps to solve or identify the problem with no avail so far:
swapping out the RAM
swapping out the graphics card
testing the HDD integrity with HD TUNE and CrystalDiskInfo
testing the Processor with Intel Processor Diagnostic Tool
testing the GPU with FurMark
updating the GPU driver to the latest version
updating the BIOS to the latest version
The hardware passed all tests with no indication of any faults. The problem persisted even when the GPU and RAM were replaced. The original GPU and RAM (listed on the pcpartpicker build) are currently in the PC.
Any other suggestions as to how I can solve this problem are very much appreciated.