Summary: Wondering which Athlon 64 CPU runs best with NVIDIA's GeForce 7800 GTX GPU? In this article, we've gathered processors ranging from the 1.8GHz "Venice" Athlon 64 3000+, all the way up to AMD's latest Athlon 64 FX-57 CPU. We've also included the GeForce 6800 GT for comparison. See which processor(s) deliver the most bang for your buck, as well as which clock speeds you may want to shoot for when overclocking inside!
What! It’s too fast? How does this happen?
On the software side, even the latest games often lag behind the newest hardware by 6-12 months. This is because hardware cycles are refreshed so quickly today that game developers can’t keep up. Whereas ATI and NVIDIA often replace their latest products every six months, a game can take (at best) 1-2 years to develop, if not longer. By the time a game is developed from start to finish, the 3D graphics landscape may have advanced by a generation or two.
The processors…a quick refresher
Sorting through AMD’s current Athlon 64 lineup can be a sizeable task. Not only do you have to worry about Athlon 64 versus Athlon 64 FX (and don’t forget the X2), but you also can’t forget AMD’s newer 90-nanometer processors. Besides the newer manufacturing process, these chips bring with them support for 11 of Intel’s 13 SSE3 instructions, lower operating voltage, and contain a tweaked memory controller which supports mismatched DIMM sizes as well as providing support for all DIMM slots to be populated without a performance slowdown. Athlon 64 cores based on this new 90-nm revision go by the name of “Venice” and contain 512KB of L2 cache, just like previous A64 processors.
Technically, purists may insist that CPU-scaling results should be taken at the lowest resolution possible (640x480 or 800x600) with image quality settings turned down, and no AA/AF. For the most part, we decided not to do this for our tests, as it isn’t something a prospective 7800 GTX or 6800 GT owner would do with their card. However, we did run a few tests with F.E.A.R. without AA/AF, although we kept the graphics settings cranked up.
Before we examine the GeForce 7800 GTX’s performance with specific processors from AMD’s lineup, let’s first take a look at how well the 7800 GTX card scales at various clock speeds. This will give us a basic idea of what clock frequencies the 7800 GTX begins to respond to.
Once again the GeForce 7800 GTX really begins to shine once we hit 2.2GHz, performance improves by 9% in both applications. Like Half-Life 2 previously, IL-2 Sturmovik scales a little better than LOMAC as we increase clock speeds – in fact going from 1.8GHz to 2.0GHz buys us another 9% in performance, and we continue to see a nice improvement when going from 2.2GHz up to 2.4GHz.
Pacific Fighters - OpenGL
Far Cry – Direct3D
IL-2: FB – OpenGL
LOMAC – Direct3D
DOOM 3 – OpenGL
Half-Life 2 – Direct3D
Splinter Cell – Direct3D
Battlefield 2 – Direct3D
NVIDIA’s GeForce 7800 GTX is an incredibly powerful graphics card. Sporting an increased number of pixel and vertex pipelines, higher clocks, and the enhancements NVIDIA has made to its G70 core, the 7800 GTX is a more than capable performer, delivering performance 1.5-2X times greater than its predecessor, the GeForce 6800 Ultra in some cases.
If you’re not careful however and pair the 7800 GTX with a slower processor, all that power can go to waste. This is because the processor isn’t fast enough to keep up with the graphics card. An analogy we’ve used in the past is putting 14” tires on a Ferrari.
Just as a 14” tire wouldn’t be capable of providing the traction needed for the Ferrari to accelerate, a slower processor prevents the 7800 GTX from hitting higher frame rates. Fortunately, AMD’s Athlon 64 processors are fast enough to keep the 7800 GTX sufficiently fed, although we obviously saw that the Athlon 64 3000+ was preventing the 7800 GTX from reaching its full potential in many cases.
Based on our testing, the sweet spot kicks in somewhere around the A64 3500+ range. Our numbers with Half-Life 2 show this most dramatically. In addition, the HL2 1024x768 results also show that the 7800 GTX benefits from the 1MB L2 cache of the 4000+ and FX processors. The scaling results on page three corroborate these findings as well, as the 7800 GTX’s performance jumps profoundly at 2.2GHz. This is probably the clock speed you should shoot for if you’re in the market for a new processor but don’t want to drain your bank account in the process; or if you can’t afford a new chip, it’s definitely the speed you should go for when overclocking.
If you’re lucky enough to afford a GeForce 7800 GTX SLI setup, you should definitely set your goals higher. In our GeForce 7800 GTX Performance Preview article, we were CPU-bound in many cases with the 7800 GTX SLI configuration even when running with an FX-55 CPU, which was the fastest processor we had at the time. We wouldn’t be surprised if 3.0GHz or more was required to truly keep a 7800 GTX SLI config running optimally.
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