ASUS P5E3 Deluxe Overclocking: DDR3 Takes Front Stage
by Kris Boughton on November 20, 2007 4:00 AM EST- Posted in
- CPUs
General Memory Performance Scaling and Command Rate
Fiddling with the BIOS to see what works and what does not is all well and good but meaningless unless we have A way to quantify the results. To that end, we've done our best to tabulate the details of our testing and present the following.
Before delving into more advanced discussions let's first review what we already know about typical memory scaling. In this graph, we show how memory responds to a simple change in base operating frequency. Here we can see the memory responds just as we expect - higher frequencies bring about higher bandwidths.
The green lines represent actual data points, collected with timings of 8-8-8-15, a Static Read Control Delay of 7 and Command Rate 1N. The blue lines represent extrapolated data points - i.e. we did not measure these values directly but rather scaled existing test results to create additional information for comparison purposes. This is an important detail to note as this means we extrapolated the data points in the context of our original tests (the same timings, etc.). While this isn't 100% accurate, it does provide a very good estimate for the timings you would most likely set at these particular speeds.
The result is an unadulterated illustration of memory read performance with frequency being the only variable - just as we intended. This also gives us the ability to predict how our memory would perform should we run it at DDR-2000 with 8-8-8-15 timings. While some choose to do this by pumping excessive voltage through their memory modules, we feel our method is safer as we do not risk damaging our expensive DDR3. Future DDR3 will likely be able to reach these higher performance settings at more reasonable voltages, however.
Our ASUS P5E3 Deluxe exhibited an amazing memory scaling range, allowing us to run our memory 1:1 at stock speeds with tight 4-4-4-12 timings and as high as about DDR-1960 at 8-8-8-15 by using the more exotic 2:1 divider. It appears our final limitation was the board/CPU combination and not the memory. We have no doubt the memory would have continued to scale well above 2GHz had there been additional FSB headroom to play with.
In this analysis, intended to show the affect of 1N versus 2N Command Rate, we see that setting 1N (DRAM Command Rate to 1T) can improve synthetic memory read scores by as much as ~3.3% over 2N. Static Read Control Delay was held constant at 7 through the use of Ai Transaction Booster while both DDR3 memory frequency and timings were increased and Command Rate was forced to either 1N or 2N by BIOS.
We can conclude that DDR-1860, 8-8-8-15-CR1 is roughly the equivalent of DDR-1925, 8-8-8-15-CR2. This means modules that might not otherwise be able to reach the speeds necessary to provide the desired target bandwidth can take advantage of the performance enhancing capabilities of the MCH in order achieve this end. In most instances enabling Command Rate 1N did nothing to bring about early instability making this setting nothing more than free bandwidth for the taking. The source of the increased bandwidth comes from the addressing efficiency improvements that come with 1N commanding and the reduction in overall memory access latency.
Fiddling with the BIOS to see what works and what does not is all well and good but meaningless unless we have A way to quantify the results. To that end, we've done our best to tabulate the details of our testing and present the following.
Before delving into more advanced discussions let's first review what we already know about typical memory scaling. In this graph, we show how memory responds to a simple change in base operating frequency. Here we can see the memory responds just as we expect - higher frequencies bring about higher bandwidths.
The green lines represent actual data points, collected with timings of 8-8-8-15, a Static Read Control Delay of 7 and Command Rate 1N. The blue lines represent extrapolated data points - i.e. we did not measure these values directly but rather scaled existing test results to create additional information for comparison purposes. This is an important detail to note as this means we extrapolated the data points in the context of our original tests (the same timings, etc.). While this isn't 100% accurate, it does provide a very good estimate for the timings you would most likely set at these particular speeds.
The result is an unadulterated illustration of memory read performance with frequency being the only variable - just as we intended. This also gives us the ability to predict how our memory would perform should we run it at DDR-2000 with 8-8-8-15 timings. While some choose to do this by pumping excessive voltage through their memory modules, we feel our method is safer as we do not risk damaging our expensive DDR3. Future DDR3 will likely be able to reach these higher performance settings at more reasonable voltages, however.
Our ASUS P5E3 Deluxe exhibited an amazing memory scaling range, allowing us to run our memory 1:1 at stock speeds with tight 4-4-4-12 timings and as high as about DDR-1960 at 8-8-8-15 by using the more exotic 2:1 divider. It appears our final limitation was the board/CPU combination and not the memory. We have no doubt the memory would have continued to scale well above 2GHz had there been additional FSB headroom to play with.
In this analysis, intended to show the affect of 1N versus 2N Command Rate, we see that setting 1N (DRAM Command Rate to 1T) can improve synthetic memory read scores by as much as ~3.3% over 2N. Static Read Control Delay was held constant at 7 through the use of Ai Transaction Booster while both DDR3 memory frequency and timings were increased and Command Rate was forced to either 1N or 2N by BIOS.
We can conclude that DDR-1860, 8-8-8-15-CR1 is roughly the equivalent of DDR-1925, 8-8-8-15-CR2. This means modules that might not otherwise be able to reach the speeds necessary to provide the desired target bandwidth can take advantage of the performance enhancing capabilities of the MCH in order achieve this end. In most instances enabling Command Rate 1N did nothing to bring about early instability making this setting nothing more than free bandwidth for the taking. The source of the increased bandwidth comes from the addressing efficiency improvements that come with 1N commanding and the reduction in overall memory access latency.
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retrospooty - Friday, November 23, 2007 - link
I should have added that beyond the current Intel roadmap, they are looking at Rambus XDR for future CPU's. DDR and its minor generational bumps arent going to cut it for long. DDR4 and DDR5 arent much better, higher speeds and higher latencies all the way = very minor performance increases.I really wouldnt advise anyone, even the enthusiests to get DDR3 now, in 1 more year Nehalem will be out with 3 channel DDR and it will likely be faster, or lower latency and cheaper than current DDR3 is, and anyone who fancies themselves and "enthusiest" will be upgrading again at that point, because 3 channel DDR3 on top of Nehalems internal memory controller WILL give a notable performance increase.
jkostans - Tuesday, November 20, 2007 - link
Spending an extra $50-100 on a GPU is still way more effective than spending the $200-300 more for DDR3. The only games that struggle with framerate on a modern mid-high end system are mostly GPU and somewhat CPU dependent. You get about the least bang for your buck with memory, but at the bleeding edge of performance I guess money is not a barrier.TA152H - Tuesday, November 20, 2007 - link
Another way to look at it is, would you rather have 1 GB of DDR3 or 2 GB of DDR2? They cost roughly the same.I'd rather have the 1 GB, since I can add more memory later. If you end up with DDR2, your system is forever degraded by inferior memory. You can't add it later unless you get a new motherboard. Besides, faster memory makes everything run faster, more memory only makes things run faster if you have to page (pretty much, I know Microsoft steals memory for caching, but that's a mixed bag anyway). Also, more memory wants more power.
I can already hear the argument from people saying that you can get 1 GB of DDR2 as well, and still realize a cost saving. It's a valid point, but at 1 GB the cost difference isn't that great, and I think the performance, and future upgradeability still make DDR3 attractive for some people.
LoneWolf15 - Tuesday, November 20, 2007 - link
Another way to look at it is, would you rather have 4GB of high-performance DDR2 for $150 (or cheaper, my 4GB of Crucial Ballistix cost me $140 this summer and is cheaper yet now), or 2GB of DDR3 for $200?
The industry must really love folks like you, who buy into the marketing hype. DDR2 is far from inferior, or Intel wouldn't have been using it all this time, and saying your system will be "forever degraded" is ridiculous tripe.
DDR3 has more bandwidth, but isn't necessarily "faster" as it is higher latency. That $150 DDR2 I mentioned has a CAS latency of 4; the $200 2GB DDR3 has a CAS latency of 7. DDR3 will only be attractive once it gains market share, lowering its price. What with enough P35 boards and some X38 boards still supporting DDR2, there is no reason to switch.
TA152H - Tuesday, November 20, 2007 - link
DDR3 is faster, if you can't accept that much, you aren't worth arguing with. DDR2 is inferior, but it's cheaper.DDR2 was not inferior until DDR3 came out. Inferior is a relative term, there has to be something better. Is English not your first language?
natebsi - Tuesday, November 20, 2007 - link
Sheesh. Personal attack much?TA152H - Tuesday, November 20, 2007 - link
Actually, you don't think his rant was a personal attack? If you don't agree with some people, you are just listening to marketing hype, or don't understand this or that. Instead of realizing there are reasons for both DDR2 (cost and compatibility) and DDR3 (everything else), you get people who accuse you of not understanding anything, and just being part of some company's marketing machine. It's so uneducated and insulting, it warrants something of the same kind back.Anyone that thinks DDR3 is completely useless, even now, is an idiot. This type of person is not worth arguing with. They are both useful, right now, and the arguments should really be about the gray areas where they begin to overlap. I might think DDR3's area is a little bigger than most, but at least I recognize that there are many people that are better off with DDR2. By the same token, I expect people to have at least basic intelligence and recognize there are areas where DDR3 makes more sense, even now. Pure performance always has a place, especially when it costs only $500, or less, more.
aeternitas - Sunday, December 9, 2007 - link
Grats on being the article clown.yyrkoon - Thursday, November 22, 2007 - link
I think the point if entirely lost on you.First, you can for instance get the same overclocks from DDR2 memory(at least from what I've seen here, because even my Promos 800 sticks can hit 1:1 475Mhz FSB which is 10Mhz faster than what I saw in the benches here).
Secondly, a system with 4GB of DDR2 vs 1-2GB of DDR3 *will* be more responsive. You can argue about it all you want, until you're blue in the face, and the only thing you will prove is that you have no actual hands on experience. Yes, this is even on a system with a 32BIT OS.
Thirdly, remember all the discussion a while back about AMD systems not performing any better than the Intel C2D systems despite having faster memory capabilities?
Lastly, even the writer of this article said the differences between the DDR2, and DDR3 system was barely a whisper . . .
But, you're right, anyone claiming that DDR3 RIGHT NOW is useless is an idiot, because they obviously can not see the eManhood effect capabilities here in saying that they paid X amount more for DDR3 vs DDR2. Anyone who has bragged about their $3000 usd set of car rims being much better than the stock rims that came with the car can surely see this point.
Griswold - Tuesday, November 20, 2007 - link
Oh yea I bet DDR3 makes perfect sense in your basement "lab" where you run your benchmarks all day long. Instead of yapping like a chihuaha with a superiority complex, you could instead just provide some realworld applications that make DDR3 not look like a waste of money right here, right now with todays hardware.Future proofing my ass, get a clue.