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Written by Hank Tolman   
Monday, 29 March 2010
Table of Contents: Page Index
Features and Specifications
Closer Look: Athlon-II X2-255
Testing and Results
EVEREST Benchmark Tests
Passmark PerformanceTest
PCMark Vantage Benchmark Tests
SiSoftware Sandra
Video Game Benchmarks
Final Thoughts and Conclusion

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.



# Great read with one flawBrian 2010-03-30 06:41
I like the read. It had great set of info for my next build, but I see a small flaw in the test. You said in the description that the FSB was eliminated because then the data transfer will be a whole lot faster than with a FSB, but I would like to know since the E6300 FSB is 1066Mhz, and the E5300 FSB is 800Mhz, what would happen with the Intel processor with a FSB of 1333MHz? The tests are sound don't get me wrong, but I would like to see what will the outcome will be with this processor. I use both AMD and Intel at home, and I see a great difference between them. but I would like to know more when it comes with a higher FSB? Still a great read, a job well done.
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# Contributing EditorHank 2010-03-30 07:40
I'm sorry, but I am extremely confused by your comment. I don't know how it would be possible to eliminate the FSB. Also, if I were to use an Intel processor with an FSB of 1333MHz it would certainly be faster than the Athlon-II X2-255, considering the least expensive of these would be a Core 2 Quad at about $160 or so. We don't need benchmarks to tell us that the Core 2 Quad will come out ahead. If I'm way off and you are talking about something else altogether, could you rephrase you question for me?
Hope this helps,

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# RE: Contributing EditorBrian 2010-03-30 08:09
Thanks for the reply, to rephrase the question, there are dual core processors that have a FSB of 1333Mhz, i.e Intel E8500. Since this is just a dual core processor, how will something like the E8500 or the E6750 go against the Athlon II X2 which has no FSB?
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# RE: RE: Contributing EditorHank 2010-03-30 09:41
Ok, I see what you mean. The processors with a 1333MHz FSB would likely all outperform the Athlon-II X2-255. The increase FSB speed would make a difference, but so would the 4MB of L2 cache. The processors used in this review were picked to test the upgradeability of the Athlon-II X2-255, and also to show its performance relative to its price. Even the E6750 will run you nearly twice what the Athlon-II X2-255, so you can expect that it will do better. But will it do twice as well as the X2-255? It's all about what you are willing to spend, as well. Paired with a 785G motherboard, like in the review, the processor/mb combo is only $150. You would be spending that on just the processor for a 1333MHz Core 2 Duo, and you wouldn't get the Radeon HD 4200. :)
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# RE: RE: Contributing EditorHank 2010-03-30 09:50
I don't there is an Intel competitor that can match the performance of the X2-255 for the same price. I think to get a processor that will beat the X2-255, you need to look at the Pentium E6500, and even that might be close. The Core 2 Duos, even the E7500 at just over $100 will outperform the X2-255, and certainly the i3-530 at $120. You'd have to compare those, however, to the Phenom-II X2-555 or maybe the Athlon-II X4-630 to get a better idea of AMD/Intel matchup.
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# RE: RE: Contributing EditorBrian 2010-03-30 14:55
Well if you put it that way than that's actually more understandable, I was just wondering why the 1333Mhz dual core processor was not on the list for some reason. But thanks for the replies, it was still a very informative reading. :)
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# RE: AMD Athlon-II X2-255 CPU ADX255OCGQBOXJohn D mathis 2011-02-04 19:24
Intersting read, informative, factual, and utilitarian. I am contemplating an upgrade on my Velocity Micro lemon, w/Intel mobo, E6600 CpU, andhaving replaced the Mobo, video card, snd card, re-installed XP Home, several times over the three years, I look longingly at the AMD line in an Asus Mobo. It appears that AMD-Asus kit would be the way to go, based on the near 20 years my Compaq (AMD cpu) has lasted w/o a hitch.Caveat other than the Creative Snd Card, always a problem configuring. Couple that with not having to replace snd, video and Net card and the value goes way up. Doing the owrk myself, a no brainer with today's modular designs, makes the AMD a GREATER value. Bit more inot the Mobo, and still save about 50% over Intel's inflated prices and w/o the arrogance of their deaf "help desk". You guys are great, saved me a tone of money, aguish and KEEP up the good work.
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