Intel P35 Memory Performance: A Closer Look
by Wesley Fink on May 18, 2007 12:00 PM EST- Posted in
- CPUs
Memory Test Configuration
In the original DDR3 vs. DDR2 review a 4MB cache E6420 was overclocked to provide 8x333 2.66GHz testing. An X6800 was used to provide the 10x266 2.66GHz configuration for comparison. For the revised tests, we used the X6800 for all testing since it was simpler to use an unlocked CPU with the flexibility to run all of the CPU configurations needed in our benchmarking. In addition we have seen some variation in the performance of different Core 2 Duo processors and we wanted to remove that variable. While we don't know exactly why, X6800 processors are often a bit faster in gaming benchmarks than some other Core 2 Duo chips. We suspected this might be distorting the real improvement in our gaming test and using the same processor removes that variable.
Memory is now also limited to Corsair DDR3 and DDR2 since there were minor variations in the performance of our two DDR3 memories. This eliminates another potential variable from the benchmarks. All other components are the same as the initial review.
Benchmarks with the P965 at 1333 FSB were not really of much use in our testing, since the memory ratios would not also allow standard memory speeds of 800 and 1066 when the bus was set to 1333. Also none of the DDR2 memory we had would run at 1333 on the P965. The P965 Is not really designed for a stock 1333 FSB so it was only tested at a 1066 FSB.
Since the P965 was not well suited for 1333 testing, the P35 was adjusted down to 1066FSB for comparison of memory performance. With that setting performance could be tested at DDR2-800 and DDR2-1066. However, a 1333 memory ratio cannot be selected with a 1066 FSB on the P35 boards that were tested, so it was not possible to run memory at 1333 and the CPU at 1066. That is the reason there are no 1333 memory speeds reported under the 10x266 CPU timings.
In the original DDR3 vs. DDR2 review a 4MB cache E6420 was overclocked to provide 8x333 2.66GHz testing. An X6800 was used to provide the 10x266 2.66GHz configuration for comparison. For the revised tests, we used the X6800 for all testing since it was simpler to use an unlocked CPU with the flexibility to run all of the CPU configurations needed in our benchmarking. In addition we have seen some variation in the performance of different Core 2 Duo processors and we wanted to remove that variable. While we don't know exactly why, X6800 processors are often a bit faster in gaming benchmarks than some other Core 2 Duo chips. We suspected this might be distorting the real improvement in our gaming test and using the same processor removes that variable.
Memory is now also limited to Corsair DDR3 and DDR2 since there were minor variations in the performance of our two DDR3 memories. This eliminates another potential variable from the benchmarks. All other components are the same as the initial review.
| Memory Performance Test Configuration | |
| Processor | Intel Core 2 Duo X6800 (x2, 2.93GHz unlocked, 4MB Unified Cache) 10x266 - 2.66 GHz 8x333 - 2.66GHz |
| RAM | Corsair CM3X1024-1066C7 (2GB Kit - 2x1GB) Corsair Dominator CM2X1024-8888C4 (2GB Kit - 2x1GB) |
| Hard Drive | Samsung 250GB SATA2 enabled (8MB Buffer) |
| System Platform Drivers | Intel - 8.3.0.1013 |
| Video Card | Leadtek WinFast 7950GT 256MB |
| Video Drivers | NVIDIA 93.71 |
| CPU Cooling | Intel Retail HSF |
| Power Supply | Corsair HX620W |
| Motherboards | Asus P5K3 Deluxe (Intel P35 DDR3) Asus P5K Deluxe (Intel P35 DDR2) Asus P5B Deluxe (Intel P965 DDR2) |
| Operating System | Windows XP Professional SP2 |
| Bench Software | SiSoft Sandra XI SP2 CPU-Z 1.40 Everest 4.0 Super Pi 1.5 Far Cry - River Demo |
Benchmarks with the P965 at 1333 FSB were not really of much use in our testing, since the memory ratios would not also allow standard memory speeds of 800 and 1066 when the bus was set to 1333. Also none of the DDR2 memory we had would run at 1333 on the P965. The P965 Is not really designed for a stock 1333 FSB so it was only tested at a 1066 FSB.
Since the P965 was not well suited for 1333 testing, the P35 was adjusted down to 1066FSB for comparison of memory performance. With that setting performance could be tested at DDR2-800 and DDR2-1066. However, a 1333 memory ratio cannot be selected with a 1066 FSB on the P35 boards that were tested, so it was not possible to run memory at 1333 and the CPU at 1066. That is the reason there are no 1333 memory speeds reported under the 10x266 CPU timings.
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TA152H - Friday, May 18, 2007 - link
I've looked over these numbers a few times, and tried to make some sense of it, and the remarks about the x6800 being slower on SuperPi, but faster on other things.There were a few clear patterns, which SuperPi managed to break, which leads me to a conclusion that this benchmark needs to be looked at closer.
For example, I noticed that DDR3 shows a greater advantage at the 1333 FSB setting, and starts leaving DDR2 behind. Except on SuperPi.
In every benchmark, 1333 FSB is faster. Except in SuperPi.
The x6800 is faster than other processors on benchmarks at the same settings, except on SuperPi.
Ummmm, anyone else think that there might be something amuck with SuperPi and it probably should be looked at more closely and possibly be removed as a benchmark until it is KNOWN to work correctly. It seems completely wrong. However, if it is reporting correctly, it would be very informative to know why it runs exactly opposite everything else. Is it using the processor in an unusual way? If so, what other applications do, so people know when to pay attention to it, and when not to.
I think the most interesting thing is how the DDR3 likes the 1333 FSB a lot more than DDR2 does. It's clearly the memory of the future.
noobzter - Friday, May 18, 2007 - link
Wes, could you elaborate on that? I've always wondered whether there's any difference between running C2Ds at higher multiplier and higher FSB (e.g. 13x267 vs 10x347)
Wesley Fink - Friday, May 18, 2007 - link
Several editors have noticed that the X6800 at the exact same speed and timing settings is a bit faster in gaming performance and a bit slower in Super Pi performance compared to other C2D processors. This is somewhat contradictory, but .We really don't know why this is the case, but we have seen it over a number of boards and in quite a few test configurations. While we don't know exactly what is different about the X6800 Extreme to make it perform this way, we do know the X6800 Extreme behaves a littel differently in benchmarks. We've asked Intel, but we have never received an answer that explained these minor differences to us.
IntelUser2000 - Friday, May 18, 2007 - link
I can explain that. When Core microarchitecture based CPUs first came out, Intel talked about being able to optimize the prefetchers for the target segment. Mobile chips would have less aggressive and power optimized prefetchers, Desktop chips would be performance optimized(relative to the mobile) and the Xeon variants would be fit for the server/workstation workloads. I would assume the "X" chips could be optimized for gaming, and that may explain the difference.
How much faster is it btw??
Wesley Fink - Saturday, May 19, 2007 - link
If you compare the 1333 gaming numbers from the ddr3 vs. ddr2 review to those in this review you will see the exact difference at the various settings. The ddr3 vs. ddr2 were run with an E6420 at 8x333, while this review used the X6800 at 8x333.Deusfaux - Friday, May 18, 2007 - link
I would guess it would have to do something with cherry picking those particular cores in the fab process and thus getting you the procs from the top of the heap that are just a wee bit better at everything and why they can also justify selling it for such a markup.yacoub - Friday, May 18, 2007 - link
I'd love to know how much performance can be gained on 650i-SLI board going from 10x266 to 8x333. I currently run 10x266 E4400 @ 2.67GHz. I wonder if I'd gain any performance running it at 8x333 and if it'd be worth the added stress to the motherboard to run at 1333MHz fsb. It's an MSi P6N-SLI Platinum.yacoub - Friday, May 18, 2007 - link
Also do I leave my PC6400 DDR2 RAM at 800MHz default or raise it a bit (they don't do 1066 very well), but I could lower them to 667MHz if for some reason it was more ideal to run a 1:2 multiplier from the 333MHz fsb than leaving them up at 800MHz.vailr - Friday, May 18, 2007 - link
Why don't you use the latest beta version Intel chipset drivers?[Instead of: System Platform Drivers Intel - 8.3.0.1013]
Version 8.4.0.1010 Beta:
http://www.station-drivers.com/telechargement/inte...">http://www.station-drivers.com/telechargement/inte...
Wesley Fink - Friday, May 18, 2007 - link
Intel tells us there are no performance imnprovements in the beta drivers. The beta drivers fix a few compatibility issues with Vista. We prefer to use release drivers unless there is a compelling performance or new release reason to use beta drivers. Gary is not testing with the new beta drivers either.