Closer Look: Phenom-II X4-975BE

The Phenom-II Black Edition processors were made for overclockers. A main concern for overclockers is always cooling. In order to push a CPU to a higher clock speed and therefore to better performance, you have to be able to keep it cool. With that in mind, the quite large 1.47" x 1.47" (37.31 x 37.31mm) heat-spreader surface area of the Phenom-II AM3 design is great for helping to dissipate excess heat. This design provides about 71% more contact surface area than recent Core i5 processors and 24% more contact surface area than Core i7 processors. With the right cooling hardware, this surface area can be taken advantage of and will allow for better overclocking.

The technical specifications for the Phenom-II X4-975BE haven't changed from previous releases of the Phenom-II X4 series; except for the 100MHz bump in clock speed, of course. The Phenom-II X4-975BE still has a nominal voltage of 0.825-1.4v and it is compatible with memory up to DDR3-1333MHz and DDR2-1066MHz. Though built on the AM3 938-pin micro pin grid array, the Phenom-II X4-975BE, like all other Athlon-II and Phenom-II processors, is backwards compatible with the AM2+ socket. Following all current AMD processors, the Phenom-II X4-975BE is built on a 45nm process. This process is becoming quite dated in the computer hardware industry as Intel has been using a smaller, 32nm process for quite some time now.

The Phenom-II series is AMD's upper echelon of CPUs and the processors differ from the lower, Athlon-II series CPUs mainly because of the addition of the L3 cache. The Phenom-II X4-975BE has a total L3 cache of 6MB shared across all four processor cores. In addition, the X4-975BE has an L2 cache of 512KB per core for a total of 2MB and an L1 cache of 512KB, 64K of L1 instruction and 64K of L1 data cache per core.

As the New Year begins, Intel is starting to release their new lineup of CPUs with the Sandy Bridge platform. Given the hype this platform has caused, it would seem like AMD is in trouble of losing the inexpensive price market. For quite a while now, AMD has been releasing processors that can outperform similarly priced Intel CPUs. In this article, we will be using one of the new Sandy Bridge processors that is being released at a similar price point to the Phenom-II X4-975BE to see how the two compare. The Phenom-II X4-975BE is set to release at $195, while the Intel Core i5-6500 is set to be released at $205. (We used the i5-6500K, but without being overclocked, it should be equal in performance to a normal i5-6500.)

Recently, nearly all of AMD's processors have proven to be great at overclocking, even those that are not Black Edition CPUs. I expected the same out of the Phenom-II X4-975BE, although it should be even easier to push this CPU due to the unlocked multiplier. The fact of the matter is, I was only able to push the Phenom-II X4-975BE from it's stock clock of 3.6GHz to a stable overclock of 4.0GHz. That's about an 11% increase in clock speed, which isn't terrible. We were able to push the other Phenom-II processor released today from 3.2GHz to 3.9GHz. That's an increase of almost 22%, nearly double the headroom we found in the Phenom-II X4-975BE. There is probably some explanation of this in the fact that the Phenom-II X4 series has been releasing updated processors using the same build now for quite a long time. Most of these processors have been able to overclock stably to about the 4.0GHz area. The X4-975BE, being a later-generation Phenom-II X4 processor, likely shouldn't have as much headroom as previous versions.

Many of our readers have recently asked me about undervolting a CPU in order to make it as utility friendly as possible. Not much is getting cheaper these days, and the price of electricity is on the list of utilities that continue to increase in price and make our lives that much more stressful. When a CPU can run at stock speeds but on less voltage than it is set for, you will see a decrease in the amount of energy the processor uses. With the Phenom-II X4-975BE processor, I was able to set the voltage to 1.2v, down from a normal 1.4v, and run it stably at stock speeds.

Since the Phenom-II X4-975BE comes with an unlocked multiplier, I started off the overclocking simply by incrementally increasing the CPU multiplier. The Phenom-II X4-975BE already starts with a very high CPU multiplier of x18. I moved the multiplier up by x1 at a time until I could no longer boot into Windows. I reached that point at a multiplier of x22. This put the Phenom-II X4-975BE at an amazing 4.4GHz. However, while I could get into Windows, the 975BE didn't withstand the stress testing I talk about in the testing methodology section. I started moving down the multiplier again by x0.5 at a time until the Phenom-II X4-975BE until the CPU passed the stress tests.

With a multiplier of x19.5 and the base clock still at 200MHz, the Phenom-II X4-975BE passed the stress testing. This put the CPU at 3.9GHz. That's a nice clock speed, but I wanted to get more out of the Phenom-II X4-975BE. I started increasing the base clock from 200MHz by an additional 5MHz. I only got to 210MHz before the Phenom-II X4-975BE failed the stress testing again. The highest stable overclock I could find was with the CPU multiplier at x19.5 and the base clock at 205MHz. I had to boost the CPU voltage to 1.6v to get to this level. This gave me an overclock of 4.0GHz, only 11% faster than the stock speeds.

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