I7 4820k seemingly locked at x12 multiplier

[DStoe]

I have the aforementioned cpu, and just recently, it's been running oddly slow. It's been overclocked just once, to a modest 4.0ghz, and was reverted back to stock not too long after. The only thing that has changed in the pc, is a new power supply (going from a 600w to a 750w). Here's all the homework I have to show:

According to the Diagnostic tool, everything is just fine. Says that it found 3.69ghz of 3.70ghz expected. However...

Cpuz shows it as a very slow core speed/multiplier setting,

This is what the Task Manager shows, running Prime95. It will not go over 32%, and reaches about a max of 1.18ghz for Speed. That Maximum Speed showed a 0.37ghz before, as an added oddness.

Probably the source of all my headaches. When I got this program, everything was showing as tinkerable. But now, the only time it shows the settings as useable, is when Core IccMax is enabled. And every time I try to enable it (it says the default is Enabled), it reboots my pc, and then says it couldn't do it (as it says with changing of pretty much any setting now).

I'm hoping this doesn't mean a damaged/dead cpu. I've been very conservative with it, never changing voltages, or running it past it's stock 95% of it's life. What can I try? It's currently set via the bios as the standard setup (x39, x37, x37, x37).

[KTran10]

Go to BIOS, under CPU configuration-->advanced Power Management, try disable EIST to see if CPU clock back to default frequency

[DStoe]

I looked in the bios for your suggestion, but there was nothing like that there. The bios is a very basic HP UEFI. The only cpu options available were Overclocking: On/Off, Voltage, and Multiplier. But I found a program called ThrottleStop, and this is what things were looking like:

After fixing the Set Multiplier to x37, and unchecking EIST, the cpu is ramping up to 3.66mhz. Turbo doesn't seem to be working, but I can live with that. Is BD Prochot or C1E anything to worry about? Thank you so very much for your help so far.