ACC/Core Unlocking On Old Chipsets

ASRock delivers a myth bust concerning ACC and core unlocking - the old AMD 480X chipset gets Phenom II X6 support and core unlocking.

Much has been written about AMD processors core unlocking and I've even detailed some steps on some occasions. It all started when AMD introduced the SB750 southbridge, which featured something called A.C.C. - Advanced Clock Calibration. It helped Phenom CPUs achieve better overclocks, back when we didn't have the 45nm "Deneb" core available. ACC delivered on the overclocking part to some extent but the true surprise was that by enabling ACC some processors would morph from Phenom X2s to X4s, X3s or unlock cache - a whole lot of fun stuff(assuming the CPU was stable).The interesting part is that it was always mostly mentioned that core unlocking was a feature restricted to ACC enabled motherboards. 

After some time, namely the launch of the AMD 8 series chipsets, it was rumored that core unlocking would not be possible since AMD had removed ACC from the new SB8x0 southbridge chips. Turns out that it is possible on all chipsets(or so it seems), it just isn't fully known how.

Behold the ASRock M3A UCC:

The M3A UCC is based on the ancient AMD 480X chipset, which was called ATI Xpress 1600 when it was released and started life as an AMD Socket 939 chipset. It still is an old PCIe 1.0 chipset and only supports HyperTransport rates up to 2GHz.

The question now is what actually enabled the core unlocking functionality, it is certainly not the southbridge since this board carries the aging SB600 - which never had ACC. Some Nvidia motherboards have surfaced that did also support core unlocking but at first this was attributed mainly to chipset revisions, something that can be now clearly confirmed that it is not the case.

One can then maybe add support to both core unlocking and Phenom II X6 processors by using Coreboot(see www.coreboot.org), as the project is currently active in adding support for these CPUs to AMD 6 and 7 series chipsets. You need some serious coding skills to do it but since the datasheets for the chipsets are available, it is indeed possible to build your own "BIOS" if you're interested.

Specs for the ASRock board:

• Phenom II X6 6-Core CPU Ready
• Supports UCC feature (Unlock CPU Core)
• Supports Dual Channel DDR3 1800(OC)
• 1 x PCI Express 1.0 x16 slot, PCIE Gigabit LAN
• PCIE Gigabit LAN
• Supports ASRock Instant Boot, Instant Flash, OC DNA, OC Tuner, IES
• AMD 480X
• SB600 Southbrige
• HyperTransport 2GHz