Chicano :
That's what I suspected before... check this thread suggestions on how to treat a possible infection.
http://www.tomshardware.com/answers/id-2188914/ram-dead.html
Follow with these suggestions if necessary
http://www.tomshardware.com/answers/id-1863469/slow.html
If you need to reinstall Windows 8 from a USB, Plop Boot Manager may help you boot it even if the BIOS doesn't have USB boot support.. the simplest way of installing Plop Boot manager is from EasyBCD... it has Plop included and can install it from "Add New Entry" / BIOS Extender... After that insert the USB drive, Start the computer, select Plop from the dual boot, and Select the USB drive.
EasyBCD Community Edition
http://www.softpedia.com/get/System/OS-Enhancements/EasyBCD.shtml
Well here's the results....
1) Malwarebyte antirootkit found nothing
2) after 9 hours, Malwarebyte found only 1 thing: an already quarantined loliport from my project64 emulator (it would install add-on junks from spigot and be difficult to remove). I had to call off the scan since 1 hour before the (force) cancelation, it got stuck on softwaredistribution folder and never changed. I clicked pause but would not pause then clicked cancel but the buttons got greyed and never stopped so I used task manager to end them. It may have come from an adobe update that cause an explorer restart. all I know is some time after the cancelation, my cpu was a max and felt like a badly fragmented disk, but it was roughly 5 percent fragmented.
3) ran a clean boot with not startups program/services but the problem was there.
4) disabled the hibernation causing 2 gb to be reclaimed but didnt resolve the primary problem
5) installed glary and cleaned registry, deleted shortcut and those kind of small stuff but nothing was gain, except a small speed up from malwarebyte. however something did caught my eye but in the end it was wish thinking that was false: in glary's context menu manager I found a thing that goes by "@%systemroot%\system32\bdeunlock.exe, -100". it's description just says
"File c:\windows\syswow64\bdeunlock.exe %1" I was hoping that disabling/unchecking the item would have fixed anything but I was disappointed.
6) ran chkdsk, sfc, and dism again and no corruption was found
7) cleared the prefetch folder
8) lastly ran the easy the easybcd community and installed plop then later a iso directory only to have both of them say the boot manager encountered a problem. the file was easyneobcd.mbr or something like that then state there was a missing or corrupt file. the program was roughly 2 years old.
The long scans are probably from the settings of the antivirus/antimalware that (for once anyway) run a full/deep scan.