|AMD Athlon-II X2-255 CPU ADX255OCGQBOX|
|Reviews - Featured Reviews: Processors|
|Written by Hank Tolman|
|Monday, 29 March 2010|
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Closer Look: Athlon-II X2-255
The Athlon-II X2-255 is based on the Regor die. Regor is a native dual core die that is 117.5 mm2 and it has a transistor count of around 234 million transistors. The die is quite a bit smaller than the Phenom-II die, Deneb. This smaller size is primarily due to the lack of L3 cache altogether. The die is built using a 45 nm process technology with AMD's Immersion Lithography, which they say allows them to put more transistors in a smaller area. The Athlon-II X2-255 also has a 65 Watt TDP (Thermal Design Power/Point). The TDP is the max amount of power dissipated by the processor under normal circumstances. It isn't the max amount of power that the processor can consume, as overclocking and other circumstances might cause the CPU to draw more power that its TDP. The 65 Watt TDP for the Athlon-II X2-255 is the same for almost all the Athlon-II X2 processors, but it is quite a bit lower than X3, X4 or Phenom lines. This means you should have less heat and power consumption to worry about under normal operating settings.
I want to mention quickly that the AMD website shows the Athlon-II X2-255 as having just 512K of L2 cache per core, for a total of 1MB. This is not correct, as is shown below by CPU-Z. Other places on the AMD website show the correct amount to be 1MB per core for a total of 2MB of L2 cache. The 2MB is in line with the other Athlon-II X2 processors, and reflects that there has not been a change in L2 cache size from the Athlon-II X2-250.
There are some differences between the Athlon-II X2-250 and its new counterpart, the Athlon-II X2-255. The first, and most obvious, is the 100Mhz bump in speed. As noted in CPUZ, the clock speed of the Athlon-II X2-255 is 3.1GHz. Another difference here is the RAM support. The X2-250 processor supported DDR2 RAM up to 800Mhz and DDR3 RAM up to 1066Mhz. The Athlon-II X2-255 bumps that up as well, increasing the compatibility with DDR2 to 1066Mhz and DDR3 to 1333Mhz. The Athlon-II X2-255 is being called Revision DA-C2.
Other than that, the X2-255 is pretty identical to the X2-250, keeping the same 200Mhz bus speed and 2000Mhz HT Link. The HT Link was bumped up by 200Mhz for the Althon-II X2 line from the Athlon X2 line. The Athlon-II X2-255 is a Socket AM3 processor, but it can be used in a Socket AM2+ motherboard as well.
The memory controller for the Athlon-II X2-255 matches the HT Link at 2000Mhz and can be configured as either one 128 bit channel or two 64 bit channels. As I mentioned before, the supported memory is listed as DDR3-1333, but just as its predecessor, the X2-250, I'm sure it will easily support the DDR3-1600 memory in our test system. Also like its predecessor, the Athlon-II X2-255 comes with full virtualization support through AMD-V technology. This will be important if you plan on using XP mode in Windows 7.
I have been a little confused since recieving the Athlon-II X2-255 processor by its exact differences with the X2-250 processor. After my research, it appears that the two chips are almost exactly the same. The core multiplier on the X2-255 is set at 15.5 rather 15 and since the X2-255 is not a black edition processor, the multiplier is locked. That is not to say that the two processors are equal in their capabilities, however. With the higher multiplier, the Athlon-II X2-255 may have better overclocking capabilities. Also, as is normal in the technology industry, having made these processors for quite a while now, AMD will have become more efficient in producing better yields. The current processors will be more stable than their predecessors, especially when pushing them to the limit. Simply by increasing the bus speed to 250Mhz, I was able to achieve a stable overclock of the Athlon-II X2-255 to 3.8GHz. The most stable overclock I found was with the multiplier set down to x15 and the bus speed increased to 255 as seen above. With a little more tweaking, you could probably get this processor up to 4.0GHz cooled by air alone.