CrystalCPUID: User Configurable Cool 'n' Quiet

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Upon launching CrystalCPUID, the following window will appear:

CrystalCPUID's main window.

Pressing F4 will open up a real-time CPU Clock:

Dot-matrix real-time CPU Clock...

Check the current multiplier of the CPU from CrystalCPUID and the core revision (Clawhammer / NewCastle / Winchester) and the current core voltage using CPU-Z.

Now, it is time to test whether CrystalCPUID can change the multiplier and voltage.

Open CrystalCPUID's main window and the Real-Time Clock by pressing F4. Pressing Ctrl-K will open the "K6/K7/K8 Multiplier" menu shown below, where the user can select new multipliers and core voltages. WARNING! Be careful with the scroll wheel!

K6/K7/K8 Multiplier menu.

BE VERY CAREFUL IN THIS MENU, since the settings apply immediately unless you check "Show Confirmed Dialog" ¬ó I strongly suggest you do this. Selecting a multiplier that is not supported by your processor (higher than the maximum or a half multiplier on some boards) will lock the computer, as will setting a core voltage that is too low for the current multiplier.

Press "Enable Change Voltage" to enable the core voltage switching. Based on the core revision of the processor, set either "4.0x/1.300 V" for "Clawhammer" revision, or "5.0x/1.100 V" for "NewCastle/Winchester" revisions. These are the default states used by Cool 'n' Quiet.

CHANGE THE MULTIPLIER FIRST. The key is to raise voltage first and lower multiplier first, to avoid the situation where the computer locks up, possibly even requiring unplugging the computer from the AC mains. The Real-Time Clock should respond almost immediately to the changes; CPU-Z shows changes after few seconds. CrystalCPUID's main window should also refresh automatically after few seconds.

If the speed doesn't change, you are out of luck; CrystalCPUID doesn't support your motherboard. Search the SPCR forums and the web for possible fixes.


If the switch is successful, it's time to test the stability. Testing with "official" state (which we have just switched to) will determine whether the system is stable in the first place. Some motherboards are unstable with some RAM and/or memory configurations.

First, shut down all unnecessary applications. Start Prime95, click Options and select "Torture Test...". From the opened window, select "In-place large FFTs" and click OK. Let it run at least few hours, optimally 24 hours. During this time, the computer is basically unusable, unless you would like to try out what computing was all about in early 90s.

If, for some reason the test results in error, you should loosen memory timings and/or set the command rate for memories to 2T. Both of these options are found somewhere in the BIOS. The Command Rate option is core specific; it's for Newcastle and Winchester care revisions only. If Prime95 still crashes, you might have incompatible memory and/or your motherboard supports only one stick of memory with CnQ. This is a problem with some S754 motherboards. (See the SPCR list of Cool 'n' Quiet compatible motherboards.)


Before we continue the configuration process, a few words about CrystalCPUID's version of Cool 'n' Quiet. Understanding how the Multiplier Management works is the basis for a functional and useful setup.

The setup window for the Multiplier Management looks like this. Note that visual appearance and functionality might differ based on the version installed.

There are three user configurable settings (states) for multiplier and voltage:

  • Minimum
  • Middle
  • Maximum

Each state has its own Interval Time and Up/Down thresholds.

  • Interval Time sets the minimum time for which the state stays "on" once entered.
  • Up/Down thresholds determine the limits for state changes for each state (CPU usage higher than the threshold -> go to next state and vice versa).

In the Option-field one can set the exit mode (if one stops Multiplier Management, which state is used), setting for Colorful Icon in the Tray (shows which state currently on) and Wait Time between the FID/VID changes. Up/Down-fields set up the way in which the states are changed. The choice here is limited to use the middle state or not. Based on the Interval Time lengths, it might be a good idea to go directly to max state from min state.

There are no "correct" settings for Multiplier Management. Basically one can use just two states (like I did with ClockGen). Or, one can set all the states below the default, which effectively makes a desktop CPU into a mobile one. Or, one can just mime the original AMD states (available here:, but with lowered voltages (and keeping in mind that there are only three states in CrystalCPUID).

As there are many workable ways to configure CrystalCPUID, the rest of the guide is based on miming AMD default states for my 3000+ NewCastle but with lowered voltages for each state. The process of testing the settings can be used for any setup.

Here are the AMD's default states; Thermal Design Power stands for maximum heat output in a state.

ADA3000AEP4AX Model Number 3000+
Max: 2000 MHz
Intermediate: 1800 MHz
Min: 1000 MHz
1.50 V
1.40 V
1.10 V
Thermal Design Power*
89 W
67 W
22 W
(*These are the maximum values for the hottest processors of the series, so the real power of the 3000+is lower.)

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