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Old 10-30-2007
graysky graysky is offline
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Default Memory bandwidth tests... any real differences (PC5300 vs. PC8888)

Common sense tell you that higher memory bandwidth should mean faster results, right? I set out to put this thought to the test looking at just two different memory dividers on my o/c'ed Q6600 system. At a FSB of 333 MHz, the slowest and fastest dividers I could run are:

1:1 a.k.a. PC5300 (667 MHz)
3:5 a.k.a. PC8888 (1,111 MHz)



Just for reference, as they relate to DDR2 memory:
Code:
PC4300=533 MHz
PC5300=667 MHz
PC6400=800 MHz
PC7100=900 MHz
PC8000=1,000 MHz
PC8500=1,066 MHz
PC8888=1,111 MHz
PC10600=1,333 MHz
The highest divider is 1:2 aka PC10600 (1,333 MHz) and it just wasn't stable with my hardware @ 333 MHz.

All other BIOS settings were held constant:
FSB = 333.34 MHz and multiplier = 9.0 which gives an overall core rate of 3.0 GHz.
DRAM voltage was 2.25V and timings were 5-5-5-15-4-30-10-10-10-11.

You can think of memory bandwidth as the diameter (size) of your memory's pipe. Quite often, the pipe's diameter isn't the bottle neck for a modern Intel-based system; it is usually much larger than the information flow to/from the processor. Think of it this way, if you can only flush your toilet twice per minute, it doesn't matter if the drain pipe connecting your home to the sewer is 3 inches around, or 8 inches around, or 18 inches around: the rate limiting step in removing water from your home is the toilet flushing/recycling and the pull of gravity, not the size of your drain line. The same is true for memory bandwidth.

After seeing the data I generated on a quad core @ 3.0 GHz, I concluded that this toilet analogy is pretty true: the higher memory bandwidth gave more or less no appreciable difference for real world applications. Shocked? I was.

Further, I should point out that in order for my system to run stable in PC8888 mode @ a FSB of 333, I had to boost my NB vcore two notches and raise my ICH to the max (both of which the BIOS colored red meaning "high risk.") The increased voltage means more heat production, and greater power consumption -- not worth it for small gains realized in my opinion. Anyway, the test details and results are below if you want to read on.



Relevant test hardware:

Motherboard: Asus P5B-Deluxe (BIOS 1215)
CPU: Intel C2Q - Q6600 (B3 revision)
Memory: Ballistix DDR2-1066 (PC2-8500)

"Real-World" Application Based Tests

I chose the following apps: lameenc, x264, winrar, and the trial version of Photohop CS3. I ran these tests on a freshly installed Windows XP Pro SP2 machine.

Lame version 3.97 Encoded the same test file (about 60 MB wav) with these commandline options:
Code:
lame -V 2 --vbr-new test.wav
(which is equivalent to the old -alt-preset fast standard) a total of 8 times and averaged play/CPU data as the benchmark.

x264 version 0.55.663 Ran a 2-pass encode on the same MPEG-2 (720x480 DVD source) file 5 times totally and averaged the results. Without getting into too much detail, the benchmark is 1,749 frames @ 23 fps. Based on these numbers, I reported the time it would take to encode 215,784 frames (which is your average 2.5 h of video @ 23 fps). Why did I do this? The differences of just 1,749 frames were too insignificant.

Shameless promotion --> you can read more about the x264 Benchmark at this URL which contains results for hundreds of systems. You can also download the benchmark and test your own machine.

RAR version 3.62 rar.exe ran my standard backup batch file which generated about 1.09 G of rars (1,654 files totally). Here is the commandline used:
Code:
rar a -u -m0 -md2048 -v51200 -rv5 -msjpg;mp3;tif;avi;zip;rar;gpg;jpg  "E:\Backups\Backup.rar" @list.txt
where list.txt a list of all the dirs I want it to back up. Benchmark results are an average of two runs timed with a stopwatch.

Trial of Photoshop CS3 The batch function in PSCS3 was used to do three things to a total of twenty-nine, 10.1 MP jpeg files:

1) bicubic resize 10.1 MP to 2.2 MP (3872x2592 --> 1800x1200) which is the perfect size for a 4x6 print @ 300 dpi.
2) unsharpen mask filter (60 %, 0.8 px radius, threshold 12)
3) saved the resulting files as a quality 8 jpg.

Benchmark results are an average of two runs timed with a stopwatch.

"Synthetic" Application Based Tests

Just two of these were chosen to illustrate a point about theoretical gains vs. real world gains. Actually, I did SuperPI for the hell of it. WinRAR served to illustrate that point.

SuperPI / mod1.5 XS The 16M test was run twice, and the average of the two are the benchmark.

WinRAR version 3.62 If you hit alt-B in WinRAR, it'll run a synthetic benchmark. This was run twice (stopped after 100 MB) and is the average of two runs.

Raw Data - "Real-World" Apps
Lameenc play/cpu (average 8 runs) @ PC5300: 30.7935
Lameenc play/cpu (average 8 runs) @ PC8888: 30.8045
Result: PC8888 is 0.5 % faster

x264 time to encode 2.5 h DVD @ PC5300: 01:48:54
x264 time to encode 2.5 h DVD @ PC8888: 01:46:14
Result: PC8888 is 2.5 % faster

rar.exe back-up (average 2 runs) @ PC5300: 45 sec
rar.exe back-up (average 2 runs) @ PC8888: 44 sec
Result: PC8888 is 2.2 % faster

Photoshop CS3 Trial batch (average 2 runs) @ PC5300: 33 sec
Photoshop CS3 Trial batch (average 2 runs) @ PC8888: 33 sec
Result: PC8888 is 0.0 % faster

So stop right here and ask yourself if a 2-3 % gain is worth the higher voltage and heat.

Raw Data - "Synthetic" Apps

SuperPI/16M test (average 2 runs) @ PC5300: 8 m 8.546 s
SuperPI/16M test (average 2 runs) @ PC8888: 7 m 33.328 s
Result: PC8888 is 7.8 % faster

Winrar internal benchmark (average 2 runs) @ PC5300: 1,515 KB/s
Winrar internal benchmark (average 2 runs) @ PC8888: 2,079 KB/s
Result: PC8888 is 37.2 % faster

...but who uses their system exclusively running internal and synthetic benchmarks? Recall that for my 1.09 gig back up, I only gained about 2 % doing "real work" by using the higher divider. Hardrives are notorious bottle-necks in systems that serve to nullify any memory bandwidth increases. In this case the 37 % theoretical increase was translated into only a 2 % "real world" increase likely due to the hardrive/rar's ability to read/write the data. Again, this seems kinda wasteful to me.

I will admit that there might be special cases where running at high memory dividers may produce more substantial gains: apps such as folding@home or seti@home, etc. may benefit from the higher memory bandwidth since they tend to make exclusive use of the system memory bandwidth and rely much less on the hardrive. I have no data to back-up this though. Also lacking in my experiments are any game data. I'd be interested in knowing if the higher bandwidth can be leveraged by game engines such as UT3, Crysis, etc. but I also didn't look at these here.

Finally, since I held everything else constant, I didn't look at the tighter timings in 1:1 mode that people can often use which may give additional gains. For example, I can get away with 3-3-3-9 @ 1:1 vs. the slower 5-5-5-15 @ 3:5 with this memory.

Anyway, I hope you found this useful and maybe this will inspire someone else to look at the gaps pointed out above (and the gaps I haven't thought of too!)
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Last edited by graysky; 10-31-2007 at 04:22 AM.
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Old 10-31-2007
mp666 mp666 is offline
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Thanks for sharing the above data. But with the system you have and the tasks you chose it's not surprising. Encoding depends more on CPU as long as there aren't other bottlenecks. 2 GB of high speed RAM will be more than enough for the benchmarks you've preferred. Since you have a quad core running, the memory bandwidth won't play a significant role in the scenarios above. Most of code for the jobs you've chosen will very likely fit in the huge caches of todays CPUs and all or most of the data will be very likely pre-fetched so having faster memory in your tests won't help much. To really test either you'll have to find special apps the benefits from higher memory bandwidth or if P5B allows it you can disable 3 of the cores and remove one stick of memory. That will somewhat simulate an older system,it will also disable dual channel (which is not going to make a huge impact). Maybe this time pushing the RAM to higher frequencies will return some benefits. I'll overclock my main system (again) later this month (November) and will take some benchmark. I'll include a few games, too. I also have both XP Pro and Vista (both 32-bit) and read that you that you need some results from dual booting system owners, I can offer some help if you wish. But I will start after a couple weeks or so.
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Old 10-31-2007
graysky graysky is offline
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Thanks for the reply. I agree with most of what you said, but I chose the apps in part because I use them pretty frequently. Therefore, for my needs, the 1:1 divider is more or less as good as the higher divider. In other words, for the majority of what I do w/ my machine, it's equally good.

I think the best benchmark are those the test apps the user actually uses
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Old 11-06-2007
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It would be nice to see if tighter timings have any noticeable advantage over higher frequency in real world applications.
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Old 11-07-2007
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Quote:
Originally Posted by templar_m1a1 View Post
It would be nice to see if tighter timings have any noticeable advantage over higher frequency in real world applications.
Based on past testing video encoding, timings have ZERO effect. Pure CPU cycles were the key.

I agree with graysky to a point. People need to gauge their performace using the machine for it's appointed jobs. Benchmarks are simply theoretical tests.

To really stress the memory and bandwidth, run multiple encoding jobs while surfing the net and listening to music.
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Old 11-07-2007
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@YB: I think the timings can make a slight difference. See the x264 results over at techarp. Check out the "data trends" table and read the green colored section about mem timings.
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Old 11-07-2007
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I should have stated that my results are on single core Pentiums. However, I don't think much has changed. What I found was that tighter timings limited my OC. So, loose timings = more CPU speed which handily beat tight timings at a slower speed. From what I have seen, this is still pretty much the case regardless of timings or CPUs.
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Old 11-08-2007
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Thanks for taking the time to do this. If you really want a good measure of what the RAM is up to, SuperPi Mod will show you. It's the best one I've come across for measuring RAM bandwidth. Everest's benchmark section shows good stuff about the RAM, but SP is where it's at.

Maybe an update sometime?
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Old 11-08-2007
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Very true about superpi... it's the goto app if you want to optimize the memory settings. That said, you may or may not see those gains translated into more disk intensive apps such as winrar, or other apps whose rate-limiting step isn't the memory.
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Old 12-29-2007
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Default one other app

My XMS 9136 sticks decided to fry, and I bought the TWIN2X2048-6400C4DHX sticks corsair is selling so cheap, and I have noticed in some games that the ram does get a bit sluggish in LOTRO, Crysis, UT3 after about two hours or so, that it did not do with the old memory. The other thing is my metalray render times are about four times longer, with the new memory. I'm not sure how much that has to with the 2:3 divider I'm using with the new ram over being able to run 1:1 or weird one when I ran the mem at 1143, I think it was 8:15 or some such I'll have to track down my old cpuz dumps. But there does seem to difference in some apps. The games I'm not I'd have noticed if I had not been using the faster ram which did not have the bumps every once in a while. I realize LOTRO is an oline game and I thought the bumps where due to my net connection at first till the rendering was slower and crysis had the same type of bumps. So other than the rendering, which most people don't do I can see where most people would see little impact.
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