Computer became recently slow

System Specs: Windows 8.1 64-bit Intel Core i7-4700MQ CPU @ 2.40GHz, 8.0GB RAM, Intel HD Graphics 4600 / NVIDIA Geforce 750M GT

Computer has been recently slow. This includes startup programs, opening files, installing programs, booting, shutting down, and gaming. However, CPU, RAM, and DISK usage is fairly low all the time. I confirmed this through task manager when opening programs. System restores seems to be the only way to solve AND worsen the problem. I have system restored several times and sometimes it would be back to speed, but slow down later. Sometimes it would get worse after system restoring.

I have tried the following that didn't help:

1) Scanned entire system using Malwarebytes, got rid of some malwares, but they weren't the main issue.
2) Scanned entire system for viruses using Avast, no viruses detected.
3) Defragged and cleared up some fragmented files. It didn't fix the slowness though.
4) Updated all drivers to latest version.
5) Clean boot (disabled all startups/services)
6) CCleaner with registry cleaning
7) Ran chkdsk and sfc /scannow, found one error, but was it was unable to fix it.
8) TuneUp Utilities & Advanced Systemcare in attempt to speed up computer.
9) Plugged charging adapter to a different outlet.
10) As mentioned, I have tried system restoring several times. It was only a temporary fix. I am running out of system restores...
Note that I have tried running in safe-mode with clean boot. It still runs slow. Any help would be appreciated. Thanks.

 

One thing you haven't mentioned is Event Viewer. That probably contains some clues.

 

I have seen this before, and it was a failing Hard drive.

The hard drive was able to pass all tests and had no bad sectors, but changing to another, known to be working well, removed the problem.

 

Here are the event files for windows:
https://www.mediafire.com/?3fdid7m50a2o5g2
I have a whole bunch of errors and warnings in administrative events. Not sure if that is the problem. I can't save the administrative events because it gives me "The system cannot find the file specified".

 

Seems fine. Here are the results. http://puu.sh/bfQQB/53b7ead98b.png

 

I found this in your System event log. Something on the mobo appears to be throttling all the cores of your i7 and might or might not be the cause of the slowness. I would recommend having a word with your supplier about it.