PC Freezing up?

[Zerberius]

I bought a new desktop from newegg, built it myself, and recently, it's been lagging up every now and then for like a minute before resuming normal operation.

I tried to diagnose this myself ( I'm not a computer expert. ) by simply opening up task manager and making sure all the stuff inside the computer was connected properly. In the task manager's detail tab, I noticed that everytime this happened, the RAM showed that it's memory was idle and was in cache mode or something, the drives become unresponsive having no activity in them but showing that it takes near infinite amount of time to process a request ( That's 2 drives doing this. ) while the CPU throttles down to 2.0Ghz or lower, maybe higher but stays lower than normal. Ethernet connection completely dies too. Something interesting is that this only happens usually right after I just turned on the PC, keeps happening for about half an hour to an hour after turning it on, then it stop happening and the PC runs perfectly, this also happens after extended sessions. ( Not sure exactly after how long, but usually happens after I use the PC for prolonged periods. ) Anyone ever encountered or know any solution to this? I'd be happy to give more information if needed. 

CPU - Vishera 6300.
Ram - Kingston HyperX 8Gb 1600 ( 4gb x 2 )
MB - Gigabye 970A-D3P
GPU - MSI R7  260X ( Afterburner edition )
SSD - Kingston 120GB
HDD - Seagate 2TB
PSU - Rosewill green 530v.

OS - Windows 1.

Note - I'm a complete computer building newbie. I'm no coder or engineer either.

[Faa]

Tried updating the lan driver? If that won't help I'd rma that board