CPU Under-clocking issues


I've been using an AMD FX-4100 since they initially released the Bulldozer line (I know...what a sucker) and haven't had any real issues until now.

Recently, upon beginning to play Planetside 2, which happens to be very CPU intensive, I noticed that sometimes my PC's performance was severely less than at other times. I quickly found that my CPU was running at 1.4Ghz, a fraction of the standard 3.6GHz it is intended to run at when under load.

I've done a lot of research and tinkering to try and remedy the problems, including but not limited to:

1) measuring the CPU frequency using: AMD System Monitor, CPU-Z, MSI's Control Center (I have an MSI motherboard) - all of which confirm the issue of being unable to run at 3600MHz when required.

2) changing RAM speeds to ensure my CPU supports the RAM situation within my system - it does.

3) turning off all power saving features in the motherboard BIOS - things such Cool'n'Quiet, C6 Core State, Turbo Core Technology, C1E (which was disabled as default)

4) acquiring patches from Microsoft that were specifically designed for Windows 7 to counteract such an issue - apparantly some users with i5's have had similar issues in the past.

So, I'm fairly stuck with what to do at this stage. The issue tends to occur when my PC has idled for a certain amount of time (20 minutes or so it would appear) or often on the first boot of the day.

I've contacted AMD to get their take on it, but at this stage all that might be left to me is to RMA it. I'm loathe to upgrade to an 8350 or similar just to solve this issue, although it might be an option...even if the issue would go away which isn't a guarantee of course.

My system specs are:

MSI 990FXA-GD65 Motherboard
AMD FX-4100 3.6GHz Processor
Sapphire Radeon HD 6950 GPU
8GB Corsair Vengeance 1866MHz RAM (2x4GB)
Antec High Current Gamer 750W PSU
Windows 7 Professional 64-bit

Any help or information anyone might have regarding such issues would be greatly appreciated. Thanks.
4 answers Last reply
More about under clocking issues
  1. temperatures. tell us your temps at idle and load.
  2. Not able to run tests right now but from previous checks, between 30-40 degrees idle, and up to 60 degrees under load. Using stock cooler, and there is no overclock on the processor, and never has been.

    It's pretty difficult to test, as when I reset the PC it will run at 3.6GHz just fine until I leave it for a certain amount of time. I will let it idle for a while later today and run tests while its stuck at 1.4GHz most likely.

    Cheers for the reply.
  3. I've managed to recreate the situation I described.

    By leaving my PC off for roughly 30 minutes, upon first boot my processor is now running at 1400MHz and will not move above that.

    However I may have found the crux of the issue, that both CPUID HWMonitor and AMD OverDrive are showing temperatures of 255 degrees across all cores!

    This is obviously a bug or perhaps a sensor issue.
  4. A bug, 255 c sensor malfunction. 255c would kill the cpu straight away if it was true.

    The fact that it is working tells you it`s wrong.

    Anyway your problem is this.

    You have cool and quiet enabled in your bios of the motherboard.

    When the cpu is Idle,or gets too hot it throttles the core speed of the cpu back to get rid of heat build up quicker. That is what is happening.

    And why the base speed on first post is 1.4 Ghz to start off with Idle.

    As soon as it gets into windows and a program is run the clock speed will adjust and move higher.

    While doing nothing intensive like running a game it will automatically down clock the Cpu to 1.4Ghz again to idel mode.

    Till you run something requiring more cpu power or speed.

    You can set a trigger temp that it will obey on when to throttle the speed based on the heat of the Cpu, in the bios, and can change that value to a higher setting to stop the clock speed of the cpu lowering due to heat.

    Or turn off cool and quiet option off in the bios completely.
    Keep a check on the Cpu temps thought ok.

    You may need to buy a better aftermarket cooler also to solve the problem. If using the stock cooler that came with the Cpu, in the box provided.
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