DDR2 vs DDR3 myths and truths (You can't Handle the truth Edition)

Discussion in 'MacBook' started by fibrizo, Feb 19, 2009.

  1. fibrizo macrumors 6502

    fibrizo

    Joined:
    Jan 23, 2009
    #1
    After seeing this brought up over and over again, I'm tired of hearing this argument as one to buy something over another. So I will post some information so I can stop answering this in posts :) Plus it was educational for me to get all of it together in my head as well.

    We know that specwise the aluminum and poly macbook lowend models are the same now except for ram. Many claim the superiority of DDR3 as their reasoning for choosing one over the other. Lets examine the issue

    The polymac has 2gb of DDR2 @667mhz much like it's predecessors. The aluminum mac has 2gb of DDR3 @1067mhz. At first glance you might say WOW! 1067 is alot more megahertz than 667! I gotta have that.

    This doesn't figure in 3 things.

    1. DDR3 increases speed at the penalty of higher latency. In real life terms, lets simplify it alot and say that DDR2 and DDR3 are cars, and that the top speed of DDR2 in this case is 66 mph and the top speed of DDR3 is 106mph. But DDR2 has lower latency than DDR3, so lets say DDR2 only has to drive 5 miles and DDR3 has to drive 8 miles. So if the speed were the same it would take DDR3 longer cause it has a longer way to drive. DDR3 makes up for it by driving faster, and as you can see the faster you can get DDR3 the less difference the latency makes (ie that 3 miles makes less over all difference when you drive 160mph ie DDR3 1600mhz (no not availible on macbook)) What this does mean though is that at lower speeds of DDR3, there isn't much benefit as the extra latency makes the performance very similar.

    2. According to others you can upgrade your ram to DDR2 800mhz
    http://forums.macrumors.com/showthread.php?t=651330&highlight=ddr2+800
    http://discussions.apple.com/thread.jspa?threadID=1877953&tstart=0

    Now let's go back to point 1. Now if DDR2 can go 80mph over 5 miles vs DDR3 going 106mph over 8 miles, there's probably even less of a difference.


    3. The last and most important thing to remember is that computer performance is tied to all the hardware, and is bottlenecked by some things far more than others. In some benchmarking between DDR2 800mhz and DDR3 1067mhz on a PC with virtually identical hardware otherwise, the bandwidth increased from 6146 to 6613... or about 10%. Which sounds alot faster. But then they performed other benchmarks, such as super pi, which showed that
    the DDR2 800mhz finished in 46.08 seconds and the DDR3 1067mhz finished in 45.11 seconds. The difference is 0.97 seconds or a whopping 2.1% performance boost.

    http://www.anandtech.com/memory/showdoc.aspx?i=2989&p=8

    To further illustrate this here are some benchmarks with the old polymacbook vs the new aluminum macbook

    http://eshop.macsales.com/shop/Memory_Benchmark/Apple_MacBook/

    To better demostrate apples to apples, (no pun intended we'll look at the 2.4 ghz macbook aluminum vs the 2.4ghz polycarbonate) in photoshop CS3

    Lower time is better
    Macbook Aluminum 2GB ram 99.34
    Polucarbonate macbook 2GB ram 107.63

    which shows that the macbook aluminum is faster 1067 vs 667 here.

    But what happens when you upgrade to a 320gb 7200 rpm drive?

    Macbook aluminum 2gb ram stock 99.34
    Macbook aluminum 2gb ram 320gb 92.28

    how about when we upgrade the ram?

    Macbook aluminum 4gb ram stock 79.06
    Macbook aluminum 4gb ram 320gb 77.19
    Polycarbonate macbook 4gb 78.41

    The gap in performance closes to basically nothing. But it does show that upgrading the ram and the hard drive will result in far more real world benefit.

    So ideally, you could get a new nvidia whitebook 999, 4gb of DDR2 800mhz ram for 47$, and a 320gb 7200 rpm drive for about 70$, you would get a total of ~1120ish for a new laptop with 4gb and 320gb 7200rpm drive... plus you have an extra 120gb drive for backups now. You could probably even ebay your old 2gb ram for 20$ or give it to a old polycarbonate mac user :)
    The final laptop you would have would be at least in using photoshop, 37% faster at these tasks than the stock 999 notebook, 27% faster than the stock aluminum macbook for 180 dollars less.

    You could pimp out an aluminum macbook as well. Which would be 1299 + 70$ for hard drive... and 70$ for ram = 1440$ which would be according th benchmarks ~1% faster. Granted if you could get a refurb, it would only be 1099+140 = 1240, which is only 120$ more. But that is the price you pay for the aluminum enclosure. :)

    In the interest of full disclosure I do own a macbook aluminum. But I got it before they updated the poly macbook. I absolutely despise integrated intel graphics. My choice was clear then, not so much now.
     
  2. janph76 macrumors member

    janph76

    Joined:
    Oct 27, 2007
    #2
    Thanks for the info. This came just about the right time since I'm contemplating of getting an Aluminum MacBook.

    This will clear up my decision of how I would upgrade the new machine for best performance. :D
     
  3. Pixellated macrumors 65816

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    Apr 1, 2008
    #3
    Nice essay :D. I didn't actually know about the DDR3 RAM having higher latency. Can you get 1667 MHz SODIMMs? If so, will they function in a GlassBook? Benchmarks with that would be interesting.
     
  4. acfusion29 macrumors 68040

    acfusion29

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    #4
    Nice sig. :D

    And nice post OP.
     
  5. bozz2006 macrumors 68030

    bozz2006

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  6. WPB2 macrumors 6502a

    WPB2

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    #6
    What about the power savings of the DDR3 compared to the DDR2. I am pretty sure the upgrade was due to longer battery life over the speed increase.
     
  7. Freyqq macrumors 68040

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    #7
    while true, the white mb has a larger battery thus actually giving it a longer battery life than the newer one
     
  8. 55orangeave macrumors member

    55orangeave

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    #8
    I fear this may be untrue
     
  9. alphaod macrumors Core

    alphaod

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  10. Stachelsk macrumors regular

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    Dec 17, 2008
    #10
    But does the chipset handle the lower latency of the memory, and does OS X/OpenFirmware tell the chipset to use a pre-specified latency, or does it use the DIMM's CMOS value?

    You used to be able to buy DDR400 CAS 1.5, but not all chipsets supported it.
    Same for the Mac... does anyone know how it picks CAS latency values?
     
  11. fibrizo thread starter macrumors 6502

    fibrizo

    Joined:
    Jan 23, 2009
    #11
    Well I'm not certain this is the power difference. Ram takes power, I know, but the main thing is probably the backlight for the screen. Typically LED backlit is more energy efficient than CCFL, which is where most of the power savings are likely realized.

    Samsung lists on their site energy savings going from 1.8V for DDR2 to 1.5V for DDR3. However power consumption is also based on frequency, and power is Volts X amps = watts (and if you can imagine, computer ram does not have a ton of amps running through it)

    If DDR2 and DDR3 are both running at 800mhz, then according to samsung, then the DDR3 will use 72% of the power of DDR3, but if you have DDR3 1067 vs DDR2 800mhz, then the DDR3 is only using 83% of the power of DDR2. Using samsung's data if we extrapolate, DDR2-667 vs DDR3-1067 would mean DDR3 would use 93% of the power of DDR2. Samsung notes that the difference between battery life at 72% consumption (28% less power usage from memory) results in ~20mins of extra battery time comparing DDR2-800 to DDR3-800. Which figures into ~12 minutes comparing DDR2-800 vs DDR3-1067... and finally if we compare stock DDR2-667 to DDR3-1067... we get ~5 more mins of battery life. I really think the display is a big difference might be the display and powering the inverter for the CCFL. I have heard that there may be a 60% reduction in power consumption?

    One last point to take in, chipset and memory controller make a big difference in performance and battery consumption. In fact, in the anandtech article I linked to above, a more efficient memory controller can net you 16-18% increases in ram performance with no increase in ram speed or power consumption, which is almost the entire difference of DDR2-800 vs DDR3-1067

    As for faster DDR3... I know there are DDR3-1333 204pin Sodimm on newegg. I'm not sure if the Macbook would just use it as 1067 at lower latency or actually use it at 1333. If it did, that would be great and I would be all over that. (heck they make DDR3-1333 in 4GB sodimm actually) And I even see they are making a DDR3-1600 2GB Sodimm as well.
     
  12. JamesGorman macrumors 65816

    JamesGorman

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    #12
    cant you buy lower latency ddr3 ram? and if not, wont it be available?
     
  13. fibrizo thread starter macrumors 6502

    fibrizo

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    Jan 23, 2009
    #13
    As noted before, you probably will be able to buy lower latency DDR3 ram. The real question is will the macbook read the lower latency on the ram stick and use those timings, or does the macbook override those and set in default timings? No one knows until we can test this. I would be curious if it could, or we could use DDR3-1333 or DDR3-1600. But we don't know the answers... However if it is anything like my previous viao the answer would be no. It's actually outright surprising that the new polymacbook supports DDR2-800 when you plug it in at all.

    And don't get me wrong, DDR3 is faster, and will continue to get faster, which is why it's going to be the new standard. But much like when DDR2 came out, there was not much difference between the last gen of DDR and the first gen of DDR2, that changed when DDR2 ramped up in speed and decreased latency. I'm sure the same thing will occur. It's just that currently there isn't that much difference between high end DDR2 (800mhz) and low end DDR3 (1067mhz). The benchmarks for DDR3-1333 and 1600 show significant improvments.
     
  14. jav6454 macrumors P6

    jav6454

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    #14
    Nice info right there, good read and kept me interested. True there is no difference in the generations when one technology gives way to the next one. DDR2 giving way to DDR3 in this case. But as OP said, over time (I assume this could take 6 months or more) latency in the new DDR3 modules will decrease. Its just a matter of when manufacturers put out the stuff.

    However, I found that having DDR3 makes a difference as your hardware is better future proof compared to DDR2 hardware. So, basically, yes you can get a ploycarbonate MacBook; however, you will be limited to certain factors in the future as your MacBook will be stuck in DDR2. But please remember I mean a future like 4 years ahead. For now, you are fine.
     
  15. aluminumapple macrumors regular

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    Jan 7, 2009
    #15
    Thank you for posting this. I hope alot of this clears about any difference within ddr2 and ddr3 within the macbook
     
  16. JamesGorman macrumors 65816

    JamesGorman

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  17. fibrizo thread starter macrumors 6502

    fibrizo

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    Jan 23, 2009
    #17
    That's still unanswered. If the Alu macbook is limited to DDR3-1067, then there is no "Future proofing" as you are stuck with 1067 (I'm in the same boat). If it accepts DDR3-1333 or 1600 and will actually run at those speeds (and not just clock it to 1067) then yes it is somewhat future proof.

    It's pretty amazing that the new poly macbook will accept ddr2-800 and run it at that when it's not in the specs. I'm not sure apple would bless the macbook aluminum with the same capability. The only way to know is to plug in ddr3-1333 and see if A. it runs and B. does it run at 1333 or just 1067.

    To test this, just bootcamp into windows and run CPUZ. it provides alot of useful info on FSB, CPU revision number, cache etc and memory speed.

    Sadly notebooks are not as upgradeable as desktops, and you usually have to buy a new one when new tech comes out. I fully expect to have to buy a new macbook in a year or 2 when the new nehelem architecture becomes mobile and more mature. In that case it uses triple channel memory, which would require 3 dimms, and would most likely be at least 1333 or 1600.
     
  18. jav6454 macrumors P6

    jav6454

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    #18
    Well you see in laptop or desktop ram it is the cases in some instances where faster ram can be (if it allowed by hardware and software) in a slower computer (eg putting 1333MHz in a 1067MHz) of coarse, the speed will still depend on the logic board, however, those future sticks of ram might have lower latencies. Looking into the future, DDR3 is going to be mainstream while DDR2 is left behind.

    So yeah, DDR3 is more future proof.
     
  19. Mr. Wonderful macrumors 6502a

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    Feb 19, 2009
    #19
    Just looked at my stats in Bootcamp on my Unibody Macbook.

    The RAM under Windows, at least, runs at the spec-ed latency of 7. The FSB is 1066mhz, so there wouldn't be much of a benefit of running a higher speed RAM.
     
  20. Val-kyrie macrumors 65816

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    Feb 13, 2005
    #20
    Future Proofing

    Future-proofing is less important than current performance. When I had to choose between an early 08 Blackbook 2.4GHz and a late 08 unibody MB, the RAM was the least of my concerns because of the current high latency of DDR-3 (compared to DDR-2). I was able to purchase the Blackbook and load it with 4GB of Corsair's fastest (=lowest latency) DDR-2 for $40 AR. There is nothing more to upgrade in terms of memory.

    By the time DDR-3 becomes comparable in terms of price and performance, I will be ready to upgrade. So long as the RAM is upgraded before it becomes unavailable or its price increases significantly, then there is no concern over future-proofing.
     
  21. kasakka macrumors 65816

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    Oct 25, 2008
    #21
    For most tasks you won't notice any real difference between DDR2 and DDR3, no matter what speed. Tests indicate differences only in synthetic benchmarks really and even then the differences are minor.

    If overclocking a lot better memory will be useful, but I've got more than a GB extra speed out of my ol' Core2Duo E6400 with just regular 4x1GB DDR2-800. Since Macs generally aren't very overclockable this isn't really something to even consider - you'll be fine with the cheapest memory most likely.

    By the time DDR3 is standard for most modern computers there will be DDR4 or something completely different out so there goes the future proof aspect too. Considering DDR2 costs next to nothing at the moment people will probably have a hard time giving the sticks away at some point so if you need to replace faulty memory it shouldn't be a problem for years.

    At this point choosing between the DDR2 Macbook and the DDR3 aluminum Macbooks is really about saving money and whether the better heatsink body of the aluminum MB, its slightly better screen and nicer trackpad are worth it over the cheaper price (including memory upgrades) and better connectors (FireWire 400, the less problematic mini-DVI...) of the white MB.
     
  22. Jpoon macrumors 6502

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    Feb 26, 2008
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    #22
    I'd say 90% of the people that get a Macbook don't even utilize it past doing basic stuff they could do on a netbook.

    Apple makes it a point to try and use the most high-quality cutting edge stuff though, even though sometimes it might not make a difference in end user performance.
     
  23. zorahk macrumors 6502

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    #23
    Thanks for stating the obvious OP. I really needed you to tell me this.

    The point of DDR3 is the higher clockspeed should outweigh the latency increase.
     
  24. pellets007 macrumors 6502a

    pellets007

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    #24
    I like the point, because it's very true. However, this was the same topic when DDR2 was announced. In several cases, DDR was still faster than DDR2. As other hardware and software evolved though, people began seeing the difference. That said, Apple is just prepping its consumers for the change, even if it's not needed yet.

    Well, that and it looks better to the non savvy consumers comparing the difference. 3>2, logically; its just a marketing gimmick at he moment, so I perceive.;)
     
  25. fibrizo thread starter macrumors 6502

    fibrizo

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    Jan 23, 2009
    #25
    It is quite obvious. But if you looked at the results you would see that the current DDR3-1067 doesn't really give you any significant advantage over DDR2-800. How about you actually post some information backing up your claim that the higher clockspeed outwieghs the latency in this case? I have stated it will do so as DDR3 speed ramps up. ;)
     

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