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Overclocking

Overclocking the Phenom II X4 940 was an interesting experience.

It overclocked up to 3.6GHz by merely changing the multiplier - and I only had to add a +0.10 Vcore offset to stabilize the most difficult benchmarks; so I think it is fair to say that most people should be able to reach at least 3.6GHz with air cooling.

Getting to 3.8GHz was more of a problem as it involved upping Vcore to levels I did not really like raising it to, only using air cooling - even if I was using a capable Noctua-12P with two 63CFM 12cm fans. However, the CPU temperatures were under 40'C under full load, so I just kept on increasing the Vcore, until I reached a total of 1.65V (which I don't recomend without excellent cooling)

Once I got 3.8GHz rock solid, I tried for the magic 4.0GHz mark. While I could post at 4.0 GHz, run CPU-Z, any non-trivial activity would blue screen Windows. But I am quite certain that 4GHz can be exceeded with liquid cooling - or perhaps with having a bit better luck in the particular sample of the processor.

Nevertheless, I must congratulate AMD with the Phenom II X4 940, and the heat-pipe heatsink AMD ships: 3.6GHz should be within reach of most people at near-default Vcore settings simply by increasing the multiplier from 15 to 18, and 3.8GHz being quite attainable with somewhat better cooling.

This is a HUGE change from the limited overclocking available with the 65nm Phenom parts, where 3.1GHz was pretty much the top one could get from a 2.6GHz 9950 without extreme measures.

65nm Phenom X4 9650: About 500MHz OC headroom with high end air cooling

45nm Phenom II X4 940: About 800MHz OC headroom with high end cooling - and it starts at 3GHz!

FYI, the "ACC" Advanced Clock Calibration did not seem to help in reaching higher clock rates.

Power Consumption

The shrink to 45nm definitely helped the Phenom II X4 940 - the "LOADED" power consumption is 47W (20%) less than for the 65nm Phenom X4 9950 overclocked to the same 3GHz as the stock speed of the Phenom II 940. For some strange reason, the idling power consumption of the 45nm part is actually higher - I have no explanation for this.

The Phenom II X4 940 consumes 3W more than the 3.2GHz Core 2 Quad QX9770 - so it looks like that architecture is still a bit more miserly with electricty.

Conclusion

Before summarizing the benchmark results, we have to consider a few things:

Pricing (as of January 7th, 2009)

• The Phenom X4 9950 is now priced significantly lower - about $170 from web shops
• The QX9650 is $1030, and the Q9650 is $550 (The QX is unlocked, but otherwise the same as the Q)
• The QX9770 is $1400
• The Core i7 920 is $295 - but needs a $250+ motherboard and wants triple channel DDR3, so its about $200 more expensive to buy due to additional motherboard and memory costs
• announced 1k OEM pricing for the Phenom II X4 940 is $275, I'd expect around $300 retail
• announced 1k OEM pricing for the Phenom II X4 920 is $235, I'd expect around $250 retail

Usage Pattern:

• no one is going to game at 640x480 / 800x600 at low detail, no AA/AF so those results don't carry much weight for gaming
• very few people actually spend a lot of time rendering 3D graphics
• except for video professionals, only a small percentage of a computers on-time is used for transcoding

Ok, so what have the benchmarks shown us?

When comparing the Phenom II X4 940 to the Phenom X4 9950 we get:

Over our testing, the Phenom II X4 940 beat the stock Phenom X4 9950 on average by 18.2%, and when the X4 9950 was overclocked to the same 3.0GHz as the Phenom II X4 940, it was still beaten by 8.8% on average, by the 940!

Comparing the Phenom II X4 940 to the Core 2 quad Q9650, the Phenom II wins in six of the tests, loses in 9, and ties in 5 - basically winning for business use, losing for transcoding/rendering and tieing for gamers.

The Core 2 Quad QX9770 pretty much has the same relative result as the Q9650, winning for business use, losing for transcoding/rendering and tieing for gamers.

The Core i7 920 loses in two cases, wins in 20, and ties in the gaming cases.

I'll get to the punch line right now.

For gamers, who have a nice video card - say at least an ATI Radeon HD 4830 or Nvidia 8800GT - and game in at least 1280x1024 with some eye candy turned on - the processor does not matter much, and I really doubt they would notice a performance difference between the $1400 QX9770, the $200+ more expensive Core i7 920 setup, or a Phenom II X4 940 running even at stock speed. The GPU matters far more in this situation, and they'd get more gaming bang for the buck by getting a better video card than a "faster" processor.

For business use, Business Winstone puts the Phenom II X4 940 right at the top of the heap - beating the much more expensive Intel setups as well as its less expensive predecessor - but frankly, even the older Phenom X4 9950 is more than enough horse power for most business uses.

For casual home use, all of these processors are way over powered, so take your pick.

Now we come to the category where the Phenom II X4 940 is not the best choice: video transcoding and graphics rendering.

If you are a video professional, and make money transcoding and rendering, spend the bucks on a high end Core i7 system - you will spend a lot more, but you will also render & transcode far faster.

Mind you, with both Nvidia and ATI releasing GPU accelerated transcoding software, and GPU accelerated rendering for non-gaming professional applications starting to appear, even this category may not need the raw processor performance of a Core i7 system that much longer.

Now some of you may argue with my conclusion, saying that more processor power never hurts. You'd be partially correct in the absolute sense - however for high end gaming, with the current generation of GPU's, it simply does not matter much - once you reach a certain level of processor performance required to keep the hungry GPU's fed.

Personally, if I was building a gaming machine right now, I'd probably get a Phenom II X4 940 with a nice 780GX or 790GX motherboard with good DDR2 memory, and spend whatever I had available to buy the most GPU power I may need - an Radeon HD 4830 or Nvidia 8800GT thru 4870's CrossFired or the upcoming GT295 SLI'd. Most users would find a single HD 4830 or 8800GT could do the trick.

If I needed a video editing / transcoding / rendering machine, I'd bite the bullet and get a Core i7 940 or 960, and save money on the video card - unless those GPU based transcoders and renderers can make good use of it.

Who knows - maybe the next generation (or two) of GPU's will change the CPU/GPU balance once again and need more powerful CPU's to feed them - but currently, a Phenom II 940 will do just fine, at a quite affordable price.