CPU Usage,Freezing,GFXLagg,Overheating..

Computer Specs:
Tech Support Guy System Info Utility version 1.0.0.2
OS Version: Microsoft Windows 7 Ultimate, Service Pack 1, 64 bit
Processor: Intel(R) Core(TM) i7-4770K CPU @ 3.50GHz, Intel64 Family 6 Model 60 Stepping 3
Processor Count: 8
RAM: 8130 Mb
Graphics Card: NVIDIA GeForce GTX 660, -1024 Mb
Hard Drives: C: Total - 1907626 MB, Free - 1578121 MB;
Motherboard: ASUSTeK COMPUTER INC., Z87-A
Antivirus: Microsoft Security Essentials, Updated and Enabled

Hello! I've been having major computer problems lately.. major effects that may be malware....
-GFX Lagg
-CPU Usage Increase randomly
EX: Lets say I'm playing a game,watching a youtube vid or just leaving my computer with all applications off on the desktop home screen, my computer randomly beeps from speakers, freezes for 2-3 secs, unfreezes then makes a beep tune i should say.....

Rumors of this problem...
-Malware
-Overheating: I've been running about 40 - 60 degrees Celsius
-Registry//Driver Errors.....

**I recently found a 24/7 TechSupport site that remotely logs in to your computer and use there "Test Applications" found some errors... Longstory short, they told me i need to pay $250 for them to fix my computer?!?! wtf

Please comment questions/regards to help fix this problem.... Thanks