Intel P35 Memory Performance: A Closer Look

Number Crunching and Gaming

The only real improvement in our tests is a 16% to 18% improvement in memory bandwidth on P35, whether it is running DDR2 or DDR3. Does the memory bandwidth improvement translate into any real improvement in system performance? Where there are performance improvements are they likely attributable to the improved memory controller or the faster CPU bus?

SuperPi 1.5 at a 2M setting was run in all memory and speed configurations. This utility benchmarks system performance in pure number crunching as it calculates pi to the number of decimal points selected (in this case 2 million). SuperPi is a very simple program but due to the size of the data set memory performance is often a critical factor.

Super Pi 1.5 - 2.66GHz Time in Seconds - Lower is Better
Memory Speed	P965 ASUS P5B Dlx	P35 DDR2 ASUS P5K Dlx	P35 DDR3 ASUS P5K3 Dlx
10 x 266 - 1066 FSB - 2.66GHz
DDR2-800 3-3-3-9	46.05	45.59 (-1.0%)	-
DDR2-800 5-6-6-15	47.28		-
DDR2-800 6-6-6-15	-	46.77 (-1.1%)	-
DDR3-800 6-6-6-15	-	-	46.95 (-0.7%)
DDR2-1067 4-4-3-11	45.39	45.03 (-0.8%)	-
DDR2-1067 5-6-6-15	45.72	-	-
DDR2-1067 6-6-6-15	-	45.16 (-1.2%)
DDR3-1067 7-7-7-20	-	-	46.03 (+0.7%)
8x333 - 1333 FSB - 2.66GHz
DDR2-800 3-3-3-9	-	45.78 (-0.6%)	-
DDR2-800 6-6-6-15	-	46.08 (-2.5%)	-
DDR3-800 6-6-6-15	-	-	46.89 (-0.8%)
DDR2-1067 4-4-3-11	-	45.20 (-0.4%)	-
DDR2-1067 6-6-6-15	-	45.81 (-0.2%)	-
DDR3-1067 7-7-7-20	-	-	45.93 (-0.5%)
DDR3-1333 9-9-9-25	-	-	45.77

With all tests run with the same X6800 CPU at 10x266 and 8x333 processor speeds, there was no clear performance improvement in SuperPi. It is interesting that most of the best (lowest) SuperPi results were with the P35 at 1066 processor bus. In most cases SuperPi performed better at 10x266 2.66 than at 8x333 2.66 which was something of a surprise. SuperPi performance is a very slightly better as a result of the P35 controller. The 1333 performance is still a bit faster than the P965, but the faster processor bus seems to actually degrade SuperPi performance a tiny amount.

Gaming

A standardized game benchmark was chosen from our memory test suite to determine if the better P35 memory bandwidth improved gaming performance. The Far Cry - River demo was run for 3 loops and results in fps were averaged over the 3 runs. This benchmark was chosen because we are familiar with how it behaves in memory performance tests. A full suite of gaming tests will be run in the P35 performance launch on May 21st.

Far Cry - HOC River Time in Frames Per Second - Higher is Better
Memory Speed	P965 ASUS P5B Dlx	P35 DDR2 ASUS P5K Dlx	P35 DDR3 ASUS P5K3 Dlx
10 x 266 - 1066 FSB - 2.66GHz
DDR2-800 3-3-3-9	101.26	106.01 (+4.7%)	-
DDR2-800 5-6-6-15	97.76		-
DDR2-800 6-6-6-15	-	102.80 (+5.2%)	-
DDR3-800 6-6-6-15	-	-	102.29 (+4.6%)
DDR2-1067 4-4-3-11	103.04	107.65 (+4.5%)	-
DDR2-1067 5-6-6-15	102	-	-
DDR2-1067 6-6-6-15	-	106.06 (+4.0%)
DDR3-1067 7-7-7-20	-	-	104.62 (2.6%)
8x333 - 1333 FSB - 2.66GHz
DDR2-800 3-3-3-9	-	106.30 (+5.0%)	-
DDR2-800 6-6-6-15	-	103.01 (+5.4%)	-
DDR3-800 6-6-6-15	-	-	103.39 (+5.7%)
DDR2-1067 4-4-3-11	-	108.00 (+4.8%)	-
DDR2-1067 6-6-6-15	-	106.61 (+4.5%)	-
DDR3-1067 7-7-7-20	-	-	105.87 (+3.8%)
DDR3-1333 9-9-9-25	-	-	106.7

Using the same CPU for all tests actually shows greater improvements in gaming performance than was seen in the DDR3 vs. DDR2 review. As you can see in the comparisons above the P35 memory controller contributed 3 to 5% improvement in gaming performance. Our target DDR-800 results showed a 4.6% to 5.2% improvement, so we conclude the P35 memory controller improves gaming performance roughly 5%

Results below the 1333 line represent total improvement, which varied from about 4% to 6%. With the target DDR-800 performance improvement ranging from 5.4% to 5.7% total, and the memory controller alone contributing 5% improvement, we are left with about 0.5% performance improvement in gaming due to the higher processor bus.

These results were a bit of a surprise. Almost all of the improvement in real-world gaming came as a result of the improved P35 memory controller, with about half a percent attributable to the 1333 processor bus. The Far Cry benchmarks show most of the real world gaming improvements are the result of the P35 memory controller.