AMD Phenom II X4 975 & 840 Review

ajmatson - 2010-12-15 06:27:26 in CPU's
Category: CPU's
Reviewed by: ajmatson   
Reviewed on: January 3, 2011
Price: Approx. $100 & $200


With the turn of the year, AMD is working hard to keep updating its current processor line. As with most manufacturers, tweaks to current designs lead to new speed boosts or even new chips based on how well the tweaking process works. AMD is a big runner with chip tweaks, bringing us a slew of models and capabilities to choose from. AMD has always been great at releasing new chips aimed at every user's budget, big or small. With this latest round, AMD brings to the table a new low price Phenom II quad-core, as well as the newest quad-core flagship to replace the Phenom II X4 970. These two chips share the majority of the Phenom II characteristics with the exception of the X4 840, which allows it to become the cheapest Phenom II quad-core on the market.

Will these new chips hold up among the current leaders? We will be putting them through a set of tests designed to tell us just that. Without further ado, we will start off with a better look at the processors and what makes them each special before getting into the testing portion.


Closer Look:

The first chip we have up on the test bed today is the AMD Phenom II X4 840, a new addition to the Phenom II line that offers performance at a low cost. The Phenom II X4 840 is a quad-core processor that can be had for about $100 at launch. Not bad for a four-core processor with the Phenom II name. But, before you get all excited, this CPU is lacking in one area that other Phenom IIs have - it has no L3 cache, only L1 and L2. Will this make a big difference between other Phenom II quad-cores? Only testing will tell. Other than not having an L3 cache, the X4 840 is just like any other Phenom IIs. It has support for DDR3 and DDR2, HyperTransport 3.0 and more.













Next, we have the new top end processor for the quad-core line, the AMD Phenom II X4 975. This CPU takes the pride and glory of the X4 processors and moves into the reign of being the flagship CPU. The X4 975 is clocked at a high 3.6GHz and shares the same specs of former Phenom II X4 Black Edition processors including a 6MB shared L3 cache, 2MB total L2 cache, HyperTransport 3.0 and of course the unlocked multiplier that Black Edition CPUs have, which normally makes them better and easier to overclock.


Now that we have seen the hardware, let's pop them in and get to the testing.


Model Number:
Phenom II X4 840 (HDX840WFK42GM)
Phenom II X4 975 (HDZ975FBK4DGM)
Clock Frequency:
Max TDP:
95 Watts
125 Watts
Cache Size:
L1 Cache 64K (each for Instruction + Data)
L2 Cache: 512KB per core (2MB Total)
L1 Cache 64K (each for Instruction + Data)
L2 Cache: 512KB per core (2MB Total)
L3 Cache: 6MB Shared L3
Process Technology:
45-nanometer SOI (silicon-on-insulator) technology
45-nanometer SOI (silicon-on-insulator) technology
HyperTransport Technology Links:
One 16-bit/16-bit link @ up to 4.0GHz full duplex (2.0GHz x2)
One 16-bit/16-bit link @ up to 4.0GHz full duplex (2.0GHz x2)
Integrated 128-bit wide memory controller with speeds: Up to 2.0GHz with Dual Dynamic Power Management
Integrated 128-bit wide memory controller with speeds: Up to 2.0GHz with Dual Dynamic Power Management
Types of Memory:
support unregistered DIMMs up to PC2-8500 (DDR2-1066MHz) -AND- PC3-10600 (DDR3-1333MHz)
support unregistered DIMMs up to PC2-8500 (DDR2-1066MHz) -AND- PC3-10600 (DDR3-1333MHz)
Die Size:
Socket AM3 - 938-pin organic micro Pin Grid Array (micro-PGA) (Backwards compatable with AM2+ 940-pin)
Socket AM3 - 938-pin organic micro Pin Grid Array (micro-PGA) (Backwards compatable with AM2+ 940-pin)




All information courtsey of Advanced Micro Devices.


Here at OverclockersClub, we put our hardware through a rigorous testing program. We use a combination of scientific and video benchmarks designed to push and stress the components which, along with our own extensive experience, gives us a good idea how they will perform in everyday computing. I placed the AMD Phenom II X4 975 and Phenom II X4 840 processors up against a slew of other AMD and Intel processors so you get a good idea on where they stand among the other choices out there. All the supporting hardware is run at the same speeds, timings, voltages and latencies to ensure that there are no outside variables that will interfere with the scores.


Testing Setup: AMD AM3


Testing Setup: Intel Core i5/i7 Socket 1156


Testing Setup: Intel Core i7 Socket 1366


Testing Setup: Intel Core i5 Clarksdale Socket 1156


Comparison CPUs:



Overclocked settings:

Overclocking the processors took two different steps for each model. The Phenom II X4 975 has an unlocked multiplier, making it easier to just raise the CPU value while keeping other components (such as memory and the HyperTransport BUS) at their stock speeds thereby helping with stability. To start off with overclocking the X4 975, I raised the multiplier 1x at a time until I was no longer able to keep the system stable. I then backed down 1x and started adjusting the reference clock the same way while also pushing up the CPU voltage. With the X4 975, I was able to achieve a nice stable overclock well above 4GHz, which makes a sub $200 CPU an even better bargain. The final speed for the X4 975 was 4.32GHz. When it came to overclocking the X4 840, which has a locked multiplier, I took the same approach as above, but only with the reference clock and the voltage. I started off by increasing the clock speed 5MHz at a time until I reached a wall and then backed off 1MHz at a time. With the X4 840, I was able to push the reference clock to 240MHz for a final overclocked speed of 3.85GHz, which is a mild overclock, but this is what's expected for a lower-end chip.




Maximum Clock Speeds:

Each CPU has been tested for stability at the clock speeds listed when in an overclocked state. These clock speeds will represent the overclocked scores in the testing.




  1. Apophysis
  2. WinRAR
  3. Office 2007 Excel Number Crunch
  4. POV Ray 3.7
  5. Bibble 5
  6. Sandra XII
  7. ScienceMark 2.02
  8. Cinebench 10 & 11.5
  9. HD Tune 3.50
  1. Far Cry 2
  2. Call of Duty: Modern Warfare 2
  3. Batman: Arkham Asylum
  4. 3DMark Vantage


The first part of our testing will be the system specific benchmarks.


Let's get started with Apophysis. This program is used primarily to render and generate fractal flame images. We will run this benchmark with the following settings:



The measurement used is time to render, in minutes, to complete.














Lower is Better


WinRAR is a tool to archive and compress large files to a manageable size. We will use 100MB and 500MB files to test the time needed to compress these files. Time will be measured in seconds. Additionally, I will use the built-in benchmark as a comparison.




Lower is Better




Lower is Better


Bibble 5:



The X4 975 was on par with the other AMD Phenom II X4 processors, but the X4 840 was along the lines of the Athlon II quad-core.


Office 2007 Excel Big Number Crunch: This test takes a 6.2MB Microsoft Excel spreadsheet and performs about 28,000 sets of calculations, consisting of many of the most commonly used calculations in Excel. The measure of this test is how long it takes to refresh the sheet.




















Lower Is Better


POV Ray 3.7: This program features a built-in benchmark that renders an image using Ray Tracing. The latest versions offer support for SMP (Symmetric Multiprocessing), enabling the workload to be spread across the cores for a quicker completion.


Higher Is Better


Geekbench 2.1 provides a comprehensive set of benchmarks engineered to quickly and accurately measure processor and memory performance. Designed to make benchmarks easy to run and easy to understand, Geekbench takes the guesswork out of producing robust and reliable benchmark results.



Again, the X4 840 was on par with the Athlon II X4 and the X4 975 was the leader of the Phenom II quad-cores.


SiSoft Sandra is a diagnostic utility and synthetic benchmarking program. Sandra allows you to view your hardware at a higher level to be more helpful. For this benchmark, I will be running a broad spectrum of tests to gauge the performance of key functions of the CPUs.

















Processor Arithmetic



Multi-Core Efficiency



Memory Bandwidth



Memory Latency



Cache and Memory



Power Management Efficiency



Here, the X4 840 was a bit faster than the Athlon II X4 processor. The X4 975 was still the best AMD quad-core.


ScienceMark tests real world performance instead of using synthetic benchmarks. For this test, we ran the benchmark suite and will use the overall score for comparison.





















Higher is Better


CineBench 11.5 is the latest iteration of this popular benchmark that features a new look to the interface. This test now has a simple GPU and CPU test built in.


Higher is Better


HD Tune measures disk performance to make comparisons between drives or disk controllers.


Higher is Better



Lower is Better


The X4 975 was faster than even some of the Intel quad-cores, except in HD Tune where the AMD chipset fell. The X4 840 was still on par with the Athlon II quad-core.


Far Cry 2:

Featuring a new game engine named Dunia, this game looks to be another one to stress your video card. Built specially for Far Cry 2, this engine allows for real-time effects and damage. This next generation first-person shooter comes to us from Ubisoft, surprisingly - not from Crytek. The game is set in a war-torn region of Africa where there is a non-existent central government and the chaos that surrounds this type of social environment. If you have seen the movie Blood Diamond, you know the setting. Ubisoft puts the main storyline of the game into focus with these statements: "Caught between two rival factions in war-torn Africa, you are sent to take out "The Jackal," a mysterious character who has rekindled the conflict between the warlords, jeopardizing thousands of lives. In order to fulfill your mission you will have to play the factions against each other, identify and exploit their weaknesses, and neutralize their superior numbers and firepower with surprise, subversion, cunning and, of course, brute force." In this Far Cry game, you don't have the beautiful water, but instead the beauty and harshness of the African continent to contend with. Most games give you a set area that can be played through, while Ubisoft has given the gamer the equivalent of 50km2 of the vast African continent to explore while in pursuit of your goals.
















In Far Cry 2, the X4 840 trailed in performance, while the X4 975 held on strong.


Call of Duty: Modern Warfare 2 is the latest iteration of the venerable first-person shooter series, Call of Duty. Despite its long, successful pedigree, the game is not without substantial criticism and controversy, especially on the PC. Aside from the extremely short campaign and lack of innovation, the PC version's reception was also marred by its lack of support for user-run dedicated servers, which means no user-created maps, no mods, and no customized game modes. You're also limited to 18-player matches instead of the 64-player matches that were possible in Call of Duty 4: Modern Warfare. Despite all this, the game has been well received and the in-house IW 4.0 engine renders the maps in gorgeous detail, making it a perfect candidate for OCC benchmarking. You start off the single player missions playing as Private Allen and jump right into a serious firefight. This is the point where testing will begin. Testing will be done using actual game play with FPS measured by Fraps.



















In CoD: MW2, the X4 840 performed a bit better, especially when overclocked, while the X4 975 fell behind a bit.


Batman: Arkham Asylum is a new game that brings together two bitter rivals, the Joker and Batman. The Joker has taken over Arkham Asylum, Gotham's home for the criminally insane. Your task is to rein the Joker back in and restore order. This game makes use of PhysX technology to create a rich environment for you to become the Dark Knight.




















In Batman, both chips showed a stronger stance, remaining in the middle of the pack.


Featuring all-new game tests, this benchmark is for use with Vista-based systems. "There are two all-new CPU tests that have been designed around a new 'Physics and Artificial Intelligence-related computation.' CPU test two offers support for physics related hardware." There are four preset levels that correspond to specific resolutions. "Entry" is 1024 x 768 progressing to "Extreme" at 1920 x 1200. Of course, each preset can be modified to arrange any number of user-designed testing.




















In 3DMark Vantage, the X4 975 was again the fastest AMD quad-core, while the X4 840 was trailing in the rear of the pack along with the Athlon II X4 processor.


The two new additions to the Phenom II line bring a fresh update to AMD users. The Phenom II X4 975 offers the top-end stock performance for an excellent price, while the X4 840 gives budget conscious users the ability to build a low cost Phenom II-based system for their general computing needs. The AMD Phenom II X4 840 offers a budget entry chip that is set to retail for around $100 and offers plenty of performance for workstations and everyday computing. The higher end Phenom II X4 975 brings top-level quad-core performance with a great sub $200 price. Both have a fantastic bang-for-the-buck ratio, which will make any user's current or future AM3 system a great performer.

When it came to overclocking, the X4 840 has a locked multiplier and did not offer much in the way of overclocking, with only a 400MHz burst. That being said, for the price, they are hard to beat. The X4 975 on the other hand, is an overclocking beast, making it to 4.32GHz with ease thanks to the unlocked multiplier and a bit of tweaking. At 4.3GHz and a price tag under $200, this chip is also hard to be beat. The scores were excellent and the chip never faltered. Overall, these are two great additions to the Phenom II line and are sure to make any budget happy.