windows 8 - CPU gets stuck at 0.90 GHz and 53% usage cap

Configuration in question:

• Model - Dell 1558


• CPU - Core i7 740 @ 1.73Ghz - 2.93GHz


• RAM - 6GB DDR3 1333Mhz


• OS - Windows 8 Pro MSDN

Now this problem has started since yesterday.

My computer blanked out suddenly (like absolutely suddenly). And when I rebooted, the operation was sluggish. I figured out that the CPU was stuck at 0.90Ghz (which is the lower limit at which my i7 'rests' generally. Further, the CPU consumption at this 'low' frequecy is also capped at 53% - making my device a Quad-Core running at 450MHz (:-O). The device manager isn't showing any erroneous drivers and neither was any update installed in the vicinity of a few days.

Hence I did System Restore to a fortnight back. It took a lot of time due to the low frequency it was locked at - but once rebooted, the CPU started functioning normally. However, only a few minutes into the operation it again went back to 0.90GHz - and just stayed there. This is happening at every reboot now - a few minutes of sanity then everything is just a drag.

I don't think its an issue with the CPU heating up because the temperatures are staying within the same limits as any earlier time (HW Monitor). But, now, when I'm shutting down, it doesn't reboot immediately - as if it is overheated (which it is not - I even set the fan throttle to full 100%).

Any ideas on what the problem seems to be with my CPU and how to treat it?

Answer

Okay - so the problem is solved now - and I guess I know the true reason now. Some parts are mentioned in the comments above - so I will just summarize it up.

1. The fan was alright - except for the usual minor efficiency reduction that happens due to dust accumulation.


2. The CPU was alright - no throttling problems based on the CPU alone.


3. The problem was with the thermal paste on the graphics card chip.


4. Now in Dell Studio 1558 - the CPU and the Radeon chip are connected to the same heatsink via heatpipes. Further, the GPU is onboard. The thermal paste over the GPU had hardened due to lot of heating over-time and as a result it was not in good contact with the GPU.


5. Since the GPU would not cool appropriately, I guess the motherboard sensors would throttle the fan at full speed. And even then when it wasn't cooling properly, the system was simply under-clocking the components - both the CPU and the GPU. As a result the display performance was very sluggish - windows took several seconds to display, web pages were a crawl and so on.


6. Now the heat-sink has been replaced. And so is the motherboard - to avoid any potential overheating damage.

Thanks to all for the concern :)