Introduction

Why the need for such a guide? On several web logs there are a lot of people who upgraded their S754 platform to the new S939 with PCI Express. This is because the FX processor is not the only CPU anymore with the S939 socket. Most of these people want high HTT speeds to overclock their processor and memory so they buy Samsung TCCD or low latency memory like Winbond BH5/UTT.

Recently G.Skill PC4400/4800 became the hottest memory on the market together with OCZ PC4800 based on Samsung TCCD. This memory requires a high HTT speed, so the system must be overclocked.

A big problem that occurs when trying to reach high HTT speed is the memory that doesn’t want to run that speed although it is rated at speeds 275 or 300MHz. This results in many errors showing up in Memtest86+ and sudden BSOD in Windows. Some people might think this is caused by faulty memory, but nothing could be more untrue.

There is another culprit here, the processor on-die memory controller. The overclocking potential of every memory controller is different, there is no doubt that there are bad and good ones. In the low- and midrange processors from AMD the quality of the controller is not always consistent, this is a problem for most of the users. This is not so much an issue if you plan to buy a high end FX processor.

The low- and mid range processor at this moment are:

Newcastle A64 3500~3800+ S939

Winchester A64 3000~3500+ S939

Venice A64 3800+ S939

High end processors are:

Clawhammer A64 4000+ S939

Clawhammer FX 53/55 S939

San Diego 4200+ ~ FX 57 S939

Soon AMD will launch two new cores named “Venice and San Diego” (revision E3 and E4). These cores have an upgraded instruction set (SSE3) and a better memory controller which is capable of addressing four memory modules in Dual Channel.

Unfortunately the only way to find out if your CPU's memory controller is by testing it, the core revision or stepping does not tell you enough. All I can is recommend is; buy the most recent processor. This will increase the chance that you have a new memory controller.

The chance that you will have a “bad” memory controller on the Winchester core is 6 of 10. When you have a good controller, this does not mean you will reach those speeds 100% around DDR500~600. The RAM must be tuned, that’s why I've created this guide.