Lesson 04 – Finding your motherboard’s maximum stable reference clock speed


Before we start overclocking the CPU, we first need to find out how far we can push the ref clk.  The reference clock doesn’t contribute to performance itself but it can be used to fine tune the frequency of the CPU and the other components making sure we get the maximum performance they are capable of.  If you have a non Black Edition CPU, where the multipliers are locked and can not be increased beyond their stock setting, you will be using the ref clock to do all of your overclocking.

Overclocking the Reference Clock

Begin by raising the ref clk to 275MHz.  This value is probably greater than most motherboards can actually handle and more than you will need.  When we did that the CPU, HT Link, CPU NB and memory speeds went way up.  We’re going to turn down the multipliers so the frequency of each component is at or below their stock setting.  So for this CPU it needs to be below 3200MHz, the RAM below 1600MHz and the HT Link and CPU NB below 2000MHz. Now all of the other settings are at or below their stock settings so the only component we will be stressing is the reference clock.

The system probably won’t boot with the ref clk set to 275MHz.  250MHz is more realistic.  Just about every motherboard can handle 250MHz so it is safe. I’ll hit F10 and yes to save and exit.  The system restarted and is going into Windows.  Once in Windows we’ll start up Prime95 and use the Blend setting to stress the system.  With Prime95 running you need to look for these icons turning red and an error message inside the windows or if the system, freezes or blue screens and reboots you have gone too far. Let Prime95 run for about 15 minutes. If the system is stable, reboot, go into the BIOS {reg} and raise the reference clock by 5MHz and test again in Prime95 on the Blend setting. Continue upping the reference clock until the system becomes unstable.  Once the system becomes unstable, restart, go back into the BIOS and lower the reference clock frequency by 5MHz and test again for 30 minutes.  If the system is stable that is your maximum ref clk speed. If it fails reduce the speed until the system passes a 30 minute Prime95 Blend test. Take note of your motherboards maximum reference clock speed. As long as the speed is 260MHz or more, that should be all the ref clock speed you will need to overclock the other components.  After performing these tests on our motherboard the maximum stable ref clock speed is 270MHz.

Replacing the stock AMD cooler with a 3rd party cooler

The last thing we are going to do here in Lesson 4 is replace the stock AMD cooler with a 3rd party cooler.  We did lots of tests before we started making these videos to see how far we could overclock the CPU using the stock cooler.  Basically if we kept the CPU voltage at it’s stock setting, which in our CPU’s case was 1.4V, the CPU stayed at or below the max safe temperature of 62C.  If we increased the CPU voltage to 1.425V the CPU temp went above 62C.  To find our CPU’s maximum stable speed we need to be able to increase the voltage going to it.  This new CPU cooler should drop the CPU temp low enough for us to do that safely.

To remove the stock AMD CPU cooler I’m first going to disconnect the CPU fans power cable from the motherboard.  Next I’ll rotate the cam handle from right to left to looses the lever.  Press down on the lever and pull away from cooler on both sides of the cooler.  Then pull up on the cooler and it will come away from the CPU.  This might require some force because the thermal compound tends to be sticky.  Use a dry paper towel to remove most of the thermal compound from the CPU.  A cotton swab dipped in 90% or higher isopropyl alcohol will remove the rest.

The process for installing a 3rd party cooler onto the motherboard and CPU is different for each model of cooler.  This cooler is made by Arctic Cooling, called the Freezer 64 Pro.  It’s very similar to the Freezer 7 Pro Rev.2 we installed in the Intel Core i5 and i7 CPU overclocking videos.  Where that cooler was made to work on both Intel and AMD CPUs the Freezer 64 Pro is made specifically for AMD CPUs.

The cooler already has thermal compound applied to it and it installs basically the same way as the stock AMD cooler.  I’ll lower the cooler onto the CPU.

Around the CPU there is a retention base that is used to hold the cooler in place. The cooler attaches to the base using 2 brackets, one at each side.

First, attach the side with the locking lever to the retention module base

On the other side of the cooler use your thumb to press down and your index finger to press toward the CPU bracket.

Rotate the cam handle from the left to the right to secure the cooler to the motherboard.

Then connect the power cable to the motherboard.

Comparing the CPU temperatures from the stock cooler to the temperatures with the new cooler

I’ll power the computer up and go into the BIOS.  Back in lesson 2 we recorded the CPU’s idle and load temperatures using the stock AMD cooler.  We need to change all the frequency, multiplier and voltage settings back to defaults so we can compare the temperatures now, with the new 3rd party cooler, to what they were when the stock cooler was installed.  I’ll hit F12 to bring up the profiles and I’m going to load the default profile we saved back in lesson 3.  It has all the settings set to their defaults. I’ll press F10 and Enter to save and exit.  Back in Windows.  We want to see how much the CPU cooling has been improved. I’ll start CPU Temp to get the CPU idle temp.  It’s 28C. The idle temp with the stock cooler was 38C. That’s a 10C improvement. I’ll start Prime95 on the Blend mode just as we did in Lesson 2.  Prime95 has been running for 20 minutes and the CPU load temp is 48C. That’s a 10C improvement.

In Lesson 5 we will show how to find the maximum stable CPU speed on both a Black Edition and non Black Edition CPU.