AMD Phenom II X4 955 Black Edition Review

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While the news hasn’t been too hot for AMD this week, they aren’t letting it stop them from doing business.  Today, they’re refreshing their Dragon platform, which consists of an AMD processor, 700 series chipset and an ATI graphics card.  The core of this update centers around a new high-end processor, the Phenom II X4 955 Black Edition.  At 3.2GHz, can AMD carve themselves out a niche in enthusiast and overclocker segments, or is Intel just too powerful to beat?  Read on for our full review.


  • Manufacturing process: 45nm
  • Cache: 2MB L2 + 6MB L3
  • Power: 125W TDP

The Phenom II X4 955 is clocked at 3.2GHz with an unlocked multiplier and will cost $245, while the PII X4 945 will be clocked at 3.0GHz without the unlocked multiplier and cost $225.  The former king of the hill, the Phenom II X4 940 will continue to be sold for the time being but is already down to $190 at several online retailers.

AMD and Intel have always traded blows over who has the highest performance per clock, and it’s the simple truth that Intel is the current ringleader.  AMD suffered a bit of a misstep with the original Phenom chips, and they’ve been trying to rectify the situation with the current series, the Phenom II CPUs.  While they haven’t yet caught up clock for clock, AMD has decided to take a different tack from its big blue competitor and go after two very different segments of the market: the thrifty and the tinkerers.  Today’s news most directly affects the latter of those two groups; AMD’s trend lately has been to put out just as many Black Edition, or unlocked, CPUs as possible.

An unlocked CPU carries a few benefits that would otherwise be restricted.  While it’s often possible to achieve some pretty hardcore overclocking feats on locked processors, have the multiplier available to play around with tends to make things much, much easier.  Overclocking lets companies put out a product rated for a certain speed and leave it up to the end user to take a chance for some extra power.  Companies can get away with selling slightly slower processors, and users get to feel like they’re pulling one over on the man by getting more than they’d originally thought.  It’s generally a win-win scenario.  Despite the performance lead offered by their chips, Intel is clearly feeling some threat here.  It’s recently come out that they’ve been shipping their least expensive next generation CPU, the $279.99 Core i7 920, with an unlocked multiplier.  Our review unit went up to 3.8 GHz on air and remained fairly stable; while it could go higher, not many benchmarks could finish.

One major difference between AMD’s and Intel’s most recent CPU efforts is the issue of backwards compatibility.  Due to the major structural changes on Intel’s side, such as moving the memory controller on-die, the newest processors can’t be used in any prior board. They also require new memory.  AMD saw an opportunity here and brought out their AM3 processors, giving them the ability to lock into AM2+ chipsets.  This way, users looking for a little extra oomph can drop in a new CPU and not necessarily be forced to buy an entire new system.  The PII X4 955 is no exception, and can be put in many older motherboards, needing only a BIOS update. 

Once they’ve bought the processor, users can buy a new AM3 motherboard and DDR3 RAM at a later time, hopefully taking advantage of a lower price tag.  It’s worth noting at this point that while the new AM3 processors are backwards compatible with AM2+ motherboards, those AM2 chips are not forward-compatible with AM3 sockets.  Users may end up with a busted processor for their troubles, especially considering that the newer CPUs have two fewer pins on the bottom than their predecessors.

Our test system featured the AMD Phenom II X4 955 BE CPU, 4GB of Corsair DDR3 RAM, an ASUS M4A79T Deluxe motherboard, an OCZ Vertex 30 SSD as its main drive and, somewhat ironically, an EVGA NVIDIA GeForce GTX 275 graphics card.  Originally, we’d planned to double up on the benchmarks, testing the new processor in the backwards-compatible AM2 board as well as the newer AM3 board complete with DDR3 RAM.  When flashing the BIOS of the previous motherboard, however, something went wrong, resulting in one of our AM2+ ASUS boards being completely bricked.  No amount of resetting seemed to help out.  Regardless, press materials included by AMD suggest that the new Dragon update, with the X4 955 CPU and HD4890 video card offers around a 10% performance boost over the last high-end combo, which used the X4 940 CPU.  Testing seemed to bear this out, with most results offering a noticeable, but not outstanding, increase in performance.

Let’s take a look at a few raw numbers.

wPrime benchmark comparison results (lower numbers mean better performance)

CPU wPrime 32 time
Core i7 920 @ 2.66 GHz 9.1s

Phenom II x4 955 @ 3.79 GHz (OC)


Phenom II x4 940 @ 3.6 GHz (OC)


Phenom II x4 955 @ 3.2 GHz 11.859s
Phenom II x4 940 @ 3.0 GHz


Phenom II x3 720 BE @ 3.8 GHz (OC) 13.183s
Core 2 Extreme QX6850 @ 3GHz 13.869s
Phenom II x4 810 @ 2.6 GHz 14.397s
Core 2 Quad Q9450 @ 2.66 GHz 14.625s

The results aren’t too surprising; there’s a noticeable performance increase, though this no doubt owes more to the higher clock speeds than any particular difference in chip design.  With a little overclocking effort, the PII 955 even starts to nip at the heels of Intel’s Core i7 920, which is a pretty respectable feat.  Granted, the 920 can itself be overclocked.  AMD has been suggesting that the $245 PII 955 compares favorably to the $270 Core 2 Quad Q9550.  While there will always be those who complain that AMD’s newest tech is being compared to Intel’s last generation chips, the Q9550 is still very much on the market, and thus a target for comparison.

PCMark05 and 3DMark06 CPU test performance comparison results (higher scores mean better performance)

CPU PCMark05 CPU Test
3DMark06 CPU Test

Phenom II x4 955 @ 3.79 GHz (OC)

10815 PCMarks 5008 3DMarks

Phenom II x4 940 @ 3.6 GHz (OC)

10576 PCMarks 4745 3DMarks
Phenom II x3 720 BE @ 3.8 GHz (OC) 9899 PCMarks 4120 3DMarks
Phenom II x4 955 @ 3.2 GHz 9693 PCMarks 4242 3DMarks
Phenom II x4 940 @ 3.0 GHz 9020 PCMarks 4241 3DMarks
Phenom x4 9850 BE @ 2.9 GHz (OC) 8498 PCMarks 3875 3DMarks
Phenom II x4 810 @ 2.6 GHz 7750 PCMarks 3684 3DMarks
Phenom x4 9950 BE @ 2.6 GHz 7682 PCMarks 3551 3DMarks

The two system test suites both delivered results similar to wPrime, though it’s obvious that these tests were geared more towards higher clock speeds than multiple cores.  Granted, these are started to show their age, but it’s worthwhile to for comparison’s sake.

Audio Compression Test (lower scores mean better performance)

CPU Audio Test (HH:MM:SS)

Phenom II x4 940 @ 3.6 GHz (OC)


Phenom II x4 955 @ 3.79 GHz (OC)


Phenom II x4 955 @ 3.2 GHz

Phenom II x4 940 @ 3.0 GHz 00:00:36
Phenom II x4 810 @ 2.6 GHz 00:00:41
Phenom II x3 720 BE @ 3.8 GHz (OC) 00:01:20
Phenom x4 9850 BE @ 2.9 GHz (OC) 00:01:20
Phenom II x3 720 BE @ 2.8 GHz 00:01:22

The audio compression test takes about an hour’s worth of music in uncompressed WAV format and uses the LAME codec to compress it to 14 320k MP3 files.  The test itself is multicore aware, but it works by processing one file per core at a time, and occasionally there will be an orphan process left over after the other three cores have finished, which makes the completion time a little lopsided.  Still, the processor traded blows with the 940 and basically came out tied.


AMD has been offering their unique OverDrive software now, and have released version 3.0 in beta form for testing and review.  OverDrive aims to simplify the overclocking process for users.  Instead of playing around in the BIOS and constantly rebooting, users can pull a few sliders around and change clock speeds, multipliers and even voltage of certain components. 

What’s new in this beta over previous editions of the overclocking suite is AMD’s addition of so-called B.E.M.P., or Black Edition Memory Profiles.  When combined with certain motherboards and high-end memory, OverDrive can automatically detect and set not only the CPU settings but also memory clocks and timing.  AMD took the profiles idea one step further, too, giving users the ability to change settings based on specific programs or games.  The settings are all stored in plaintext XML files, giving consumers the ability to easily set up new profiles without a bunch of button clicks, as well as trade them amongst themselves.  Ideally, even manufacturers will get in on the action, posting new profiles with their software for maximum performance on AMD platforms.

In the past, OverDrive has been a useful utility to overclock a processor in order to run a few benchmarks, though for permanent benchmarking, it doesn’t seem to fare as strongly as setting it directly in the BIOS.  One very useful idea for OverDrive is to underclock the processor in the BIOS and then use AMD’s OverDrive or Fusion utilities to “over”clock the processor to it’s normal range or just above for demanding programs or games.  Users running the Windows 7 betas might do well to steer clear of OD’s impending 3.0 release, since it was very buggy on our 64-bit install.

While AMD’s new Dragon platform is definitely more powerful and capable than before, the leap in performance isn’t huge.  Users who have already upgraded to a Phenom II 940 and/or an HD4870 probably won’t see a good return on their money for an upgrade.  Those who’d been holding off to see what else AMD had up their sleeves are likely to be better upgrade candidates; the jump in performance will be a lot more noticeable.

Granted, there weren’t any major architecture changes, so this release was never going to be more than evolutionary, but that’s not such a bad thing.  AMD is fleshing out its latest CPU map and rebuilding a brand that can compete with Intel on price, if not on power.  It’s a risky game considering the weak financials they’ve been forced to confront lately.  Combined with their very competitive graphics segment, however, AMD continues to present a very reasonable option to Intel and NVIDIA. 

Come back later this week for our review of ATI’s HD4890, the remaining leg of the updated Dragon platform.


  • Fast quad core chip for under $250
  • OverDrive offers unique overclocker profiling opportunities
  • Great backwards compatibility


  • AM3 chips work in AM2+ boards, but not vice versa
  • Upgrading to AM3 board and DDR3 RAM may not be worth the cost



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