CPU Guide

AMD Phenom II X2 555 BE review

AMD's Fastest Dual-core - Phenom II X2 555 BE

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AMD's Incremental Update

AMD's Incremental Update

With a volley of its new Clarkdale Core i3/i5 processors, Intel has fired the first shots of 2010. It just so happens that with its cheapest Core i3 desktop processors starting from US$113 and AMD's competing products (with the exception of the Phenom II X4 processors) mostly falling below that price, Intel appears to have missed the mark.

To illustrate this point, AMD has responded with its own lineup of new processors that avoid competing with Intel's newest. New in the sense that these are models that have just been released but the less charitable will find nothing much new about them. What one finds is a minor clock speed bump of 100MHz for most of these models, which probably explains why AMD has merely incremented the model numbers by "5". So the Athlon II X4 630 (2.8GHz) that we covered previously gets a new sibling, the Athlon II X4 635 (2.9GHz).

Below are the new processors from AMD, which includes a new, low-power Phenom II X4, the 910e, which has a significantly lower rated TDP than all the others shown here, despite being a proper Phenom II class. It will also set you back by quite a premium for the power savings.

New AMD Processors
Processor Model Clock Speed L2 Cache L3 Cache Max TDP (W) Retail Price (US$) Availability
AMD Phenom II X4 910e 2.6GHz 2MB 6MB 65 169 Now (PiB)
AMD Phenom II X2 555 BE 3.2GHz 1MB 6MB 80 99 Now (PiB)
AMD Athlon II X4 635 2.9GHz 2MB Nil 95 119 Now (PiB)
AMD Athlon II X3 440 3.0GHz 1.5MB Nil 95 84 Now (PiB)
AMD Athlon II X2 255 3.1GHz 2MB Nil 65 74 Now (PiB)

 While the new processors span across AMD's dual, triple and quad-core offerings, our interest today has to do with the dual-core Phenom II X2 555 'Black Edition'. We did not get the opportunity to test the Phenom II X2 550 BE when it came out last year but AMD has finally sent us the new 555, which is based on the same core as the 550 (with a 100MHz bump), making it the fastest dual-core in AMD's lineup. This also leaves the Phenom II X2 family with two processors currently:

The Phenom II X2 Family
Processor Model Clock Speed L2 Cache L3 Cache HyperTransport Bus Memory Controller Speed Max TDP (W) Retail Price (US$) Availability
Phenom II X2 555 BE 3.2GHz 512KB x 2 6MB 2.0GHz 2.0GHz 80 $99 Now (PiB)
Phenom II X2 550 BE 3.1GHz 512KB x 2 6MB 2.0GHz 2.0GHz 80 $91 Now (PiB)

While the Phenom II X2 core is known as Callisto, you may have noticed the hefty 6MB L3 cache on it, similar to what's found on the Phenom II X4. AMD is indeed taking the time-tested route of locking two cores on those Phenom II X4 processors which didn't make the grade and selling them as dual-core Phenom II X2.

Obviously, this also means that enthusiasts or anyone with some basic Google skills can find out how to unlock these processors to its full four cores. And it involves nothing more challenging than a BIOS update for most cases. This forum thread for example has a list of possible working motherboards and BIOSes, though luck is a factor when unlocking the chip.

Based on the original selling price of around US$99 for the Phenom II X2 550 BE, that means one can potentially get a Phenom II X4 for around two-thirds the price. With the new Phenom II X2 555 BE debuting at US$99 and running at 3.2GHz, a full unlock will give one an equivalent of a US$166 Phenom II X4 955 BE. We're pretty confident that more than a few enthusiasts would try this and we will be exploring that possibility in the near future. But how does the Phenom II X2 perform in its original state? More on that in the next few pages.

** Updated as of 29th Jan, 2010 **

After our review, we went back to the Phenom II X2 555 BE and tried to unlock the cores based on observations noted online. While the process is relatively pain-free, involving a couple of BIOS settings (Automatic Clock Calibration mainly) at most, our headaches involved flashing the BIOS.

It sounds trivial right? Nothing could be more simple than flashing the BIOS nowadays with Windows-based utilities and even utilities from within the BIOS. Well, our first candidate was the ASUS M4A79T Deluxe and we wanted to use the official 1801 BIOS. So we went into ASUS' EZ Flash 2 utility and started the process. Everything appeared normal until the system rebooted and never came back.

We were confronted with a black screen and no way of recovery short of changing the BIOS chip since ASUS' recovery tool relied on a utility on its motherboard DVD that failed to work for us.

So we tried another board, the Biostar TA790GX A3+. We used a modded BIOS which supposedly supported the new processor and the capability to unlock it. Unfortunately, while the flashing was completed successfully, the board was dead after the restart. It's definitely a lesson learnt on trying unverified BIOS online. It's not too bad of an issue for us, but for end-users, the risks are just too high.

Third time lucky and all that, we decided to use another ASUS board, the M4A78T-E, an AMD 790GX board. It required a particular official BIOS (1402) to get the unlock and so we used EZ Flash again, which worked this time. We had no issues after the usual reboot. Unfortunately, the unlocking was unsuccessful. We followed the instructions and even despite our attempts to increase the voltages and lower the memory timings, the CPU-Z screen refused to report more than two cores.

As the various warnings on those unlocking guides attest, unlocking these AMD processors is not a slam dunk. We are probably unlucky in getting a sample that didn't work. If you really need a quad-core, we suggest you get a proper one rather than try this ghetto method. Not to mention the possible ill luck with BIOS flashing and it could turn out to be more costly than you thought.

** Updated as of 25th Feb, 2010 **

Ironically, while testing the Phenom II X2 555 BE further, we found that the motherboard in our test setup, the MSI 790FX-GD70 did have a new 'Unlock CPU Core' option with an update to BIOS version 1.8. Upon rebooting with the option enabled, the Phenom II X2 555 BE was found to be unlocked, with CPU-Z identifying it as the Phenom II X4 B55. A quick run through our benchmarks produced very similar scores as the similarly clocked Phenom II X4 955 (3.2GHz) so effectively, you're getting a quad-core for cheap with this method.