Athlon 64 Overclocking

Introduction

Do you want to learn how to overclock your Athlon 64 CPU? In this tutorial we will cover Athlon 64 overclocking with several tips and tricks that even users with some overclocking experience will learn something new.
Before going straight to overclocking, first you need to understand how clock is generated on Athlon 64 systems in order to make you understand how you can achieve overclocking and what is preventing your overclocking from working.
Athlon 64 (and other CPUs that use the same architecture, like Opteron and socket 754 Sempron – which are collectively known as AMD64 CPUs) uses a completely different architecture from other CPUs. Usually the memory controller is located inside the north bridge chip from the chipset, but on this CPU this device is embedded in the CPU itself. So on Athlon 64 systems memory types and capacities are defined by the CPU and not by the motherboard, as it occurs with other CPUs. For example, you cannot use DDR2 memory with socket 939 Athlon 64 CPUs, as their memory controller only accepts DDR memory. With Pentium 4, since it is the north bridge chip that controls memory, you would need to change the motherboard (and not the CPU) to make your system to accept DDR2 memory, if you had a DDR-based system.
On Figures 1 and 2 we illustrate this.

Figure 1: Architecture used by other CPUs.

Figure 2: Architecture used by AMD64 CPUs.

So instead of having just one external bus like other CPUs (this single external bus is very frequently called Front Side Bus or FSB), AMD64 CPUs have two busses: a memory bus and a HyperTransport bus. HyperTransport bus is an I/O bus used to connect the CPU to a bridge chip, connecting the CPU to other devices, like the video card.
Let’s now talk about how clock is generated on this architecture. If you want to learn more in depth about AMD64 architecture, try our Inside AMD64 Architecture tutorial.