My Santa Rosa MBP does not have 800Mhz memory-- just 667. Why?

Discussion in 'MacBook Pro' started by mach1andy, Jun 13, 2007.

  1. mach1andy macrumors regular

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    #1
    So I bought a new MBP 2 days ago and let me say this,,, the LED Backlit display is crisp and bright as hell.

    My concerns are that they aren't being sold or shipped with 800Mhz ram memory, just 667 Mhz. This The computer is very very fast but seriously, why the mismatch? I paid a premium for this computer and expected attention to detail, not dumping out the remaining warehouse inventory.


    Overall, great computer but held back by the one thing that could make it faster-- faster ram (the 2.16Ghz to 2.2Ghz processor bump isn't going to be noticeable)...

    Does anyone have any comments or suggestions? I'm thinking that if in the next few weeks, they start shipping with 800Mhz, I'm going to call in and ask for replacements.
     
  2. Sbrocket macrumors 65816

    Sbrocket

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    #2
    Santa Rosa's memory controller does not support 800MHz memory, despite the fact that the FSB is 800MHz. It doesn't have 800MHz memory because it would be throwing money down the drain; 800MHz memory would run as 667MHz memory.
     
  3. whateverandever macrumors 6502a

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    #3
    Better question...

    Why don't people read all the posts about 800MHz memory / Santa Rosa instead of repeating this question for the 25th time?

    Go find yourself some DDR2-800Mhz SO-DIMMs... as if you could buy them ;)
     
  4. mach1andy thread starter macrumors regular

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    #4
    Ars technica wrong?

    So this ARS Technica review of the 17" Santa Rosa MBP is wrong?...

    "Conclusions
    If you focus merely on the clock speed, the difference between the Rev. B and Rev. C machines is truly miniscule. After all, we're talking about a 70MHz speed bump. However, the performance gains with the Rev. C MacBook Pro belie the modest megahertz burp, due in no small part to its 800MHz front-side bus."


    http://arstechnica.com/reviews/hardware/macbook-pro-santa-rosa.ars/5
     
  5. Episteme macrumors regular

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    #5
    Santa Rosa's memory controller is only spec'd to run at 667MHz.

    The FSB runs at 800MHz, but that is only for data xfer between the CPU and the NorthBridge. Since the RAM runs in dual channel mode, this does help somewhat.
     
  6. Sbrocket macrumors 65816

    Sbrocket

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    #6
    That article, and especially that particular quote, says absolutely nothing about Santa Rosa's compatibility with 800MHz RAM. It isn't wrong at all...but that doesn't mean anything.

    I don't see what you're getting at.
     
  7. Episteme macrumors regular

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    #7
    No, they're right.
     
  8. amoda macrumors 6502a

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    #8
    Click here

    On that page do you see where it says "Processor and Memory"? You can see it specifcally says that the ram is 667mhz. The frontside bus is 800mhz, not the ram. They are two different things.

    To quote Apple:
    "2GB (two SO-DIMMs) of PC2-5300 (667MHz) DDR2 memory; two SO-DIMM slots support up to 4GB
    800MHz frontside bus"
     
  9. mach1andy thread starter macrumors regular

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    #9
    So the 800Mhz FSB is an improvement over the old 667Mhz FSB even with identical 5300 667Mhz memory?
     
  10. Episteme macrumors regular

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    #10
    Yes. Dual channel mode memory allows you to pull up to 2x64bits@667MHz (depends on circumstances).

    The FSB is 64bits@800MHz.

    Thus, your memory bandwidth can still theoretically exceed your FSB speed. In practice, memory latency etc. means it's unlikely to but it also means you're better equipped to cope with burst xfers.

    In reality this doesn't matter too much, and most of it is masked by the large L2 cache anyway.
     
  11. Fayler macrumors regular

    Fayler

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    #11
    Because not everyone has time to search for everything on the forum. Questions will be repeated. Deal with it.
     
  12. mach1andy thread starter macrumors regular

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    #12
    Good to know but didn't the last revision (B I believe) of the MacBook Pro also have this? 2x64bits@667mhz? If I am right, and this is true, the 800Mhz FSB wouldn't impact anything vs its predecessor...
     
  13. flopticalcube macrumors G4

    flopticalcube

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    #13
    It did but the FSB was limited to 667MHz. The impact is marginal, really.
     
  14. dejo Moderator

    dejo

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    #14
    Probably takes the same amount of time, if not less, to search than to compose a new thread, though.
     
  15. mach1andy thread starter macrumors regular

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    #15
    searching for "Santa Rosa" or "800Mhz" doesn't really give topics-- just embedded within other conversations I've found. Sorry for the repost, thanks for the answer!
     
  16. Episteme macrumors regular

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    #16
    Yes, its predecessor also had dual channel memory.

    Why wouldn't a faster FSB have an impact? The max mem bandwidth is great than either the 667MHz or 800MHz FSB.
     
  17. ChrisA macrumors G4

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    #17
    I think your problem is that in the very recent past computer buses were running at about the same speed as RAM. So you might think they would always be matched. But historically this is not the case. The front side bus connects the CPU to a lot more than just memory so it makes sense to have the bus run as fast as it can even if the memory is slower than the bus. So there is no "mis-match"

    I can think of one 1960's vintage mainframe where the memory was exactly 10X slower than the machine cycle. They addressed this by installing 10 memory banks and rather then a buss they used an NxN switch so as to allow 10 simultaneous memory acceses. The Mac Pro has a deign kind of like this using multiple paths to memory but then people complain about the cost.

    Expect the designs to become more interesting over the next few years. Clock speeds have hit a wall and now designers are being forced to revive 35 year old mainframe tricks. How long until the Front Side Buss is replaced by an NxM switch? It will happen.
     
  18. mach1andy thread starter macrumors regular

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    #18

    Solid reporting! Yeah, I guess I've just seen the trend of memory and FSB being matched over the past few years (I got into machines when i was a late teenager and its only been 5 years) so I can see where my assumptions would be incorrect.

    While this post was harvesting, I called Apple Care and the tech rep said that he too was a little surprised that it didn't ship with 800mhz memory. I guess its not that big of a deal to complain about but I was hoping for "the works". Thanks for your explanations!
     
  19. Episteme macrumors regular

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    #19
    FBDIMMs aren't about multiple paths to memory, they're about supporting a much larger number of DIMMs on the motherboard at an affordable cost. Routing the signals for traditional DDR is painful and causes other problems.

    IIRC, it's still just a dual-channel mem controller -- it can just pick which pairs of DIMMs it reads from as there's multiple banks.
     
  20. whateverandever macrumors 6502a

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    #20
    Then why are they posting here?
    Give me a break.

    If it hadn't been asked within the past three days, it'd be excusable.

    It's simple laziness, with the addition of a dash of stupidity (to be upset that Apple isn't including 800MHz RAM that isn't even on the market in their new MacBook Pro).
     
  21. whateverandever macrumors 6502a

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    #21
  22. daveL macrumors 68020

    daveL

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    #22
    Because not everyone has time to repeatedly answer the same question. Forums should be searched. Deal with it.
     
  23. Sbrocket macrumors 65816

    Sbrocket

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    #23
    Says the newbie. Forums have a search feature because its meant to be used, and the forum greatly loses its usefulness when the only things on the front page are questions that have already been answered many, many times before. Not every question needs a new thread. Chances are unless its something new, its already been answered. And forum search takes no time at all, much less than posting a new thread and waiting for someone to post a quality answer. In other words, searching the forum doesn't take potentially days. Deal with it.
     
  24. Butthead macrumors 6502

    Butthead

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    #24
    True enough, but....

    there is also the problem that even when people post the same question over and over again, we seem to repeatedly (check the posts above) get wrong information being touted as "facts". The other posters on this thread need to also do a search and find out why they are *wrong*, and stop posting wrong information on MR. SR chipset should be able to use 800Mhz SODIMM even if Intel hasn't publicly stated in their older product pdf's whether or not the SR memory controller chip will support 800Mhz DDR2, they have only said what at the time was available 667 & 533Mhz are supported, not whether or not 800Mhz can run at 800Mhz should they be used by manufacturers when they are commonly available (they are available now, through Crucial and others @$200/2GB stick last time I checked, but probably a little lower this week and lower still next month). Why Apple shipped w/o 800Mhz? Probably because of the price differential/supply issues of the more currently more expensive (heh, I'll bet Apple's got a small profit built into even the included 667Mhz mem) 800Mhz mem. didn't make any sense to their profit margins, given a slight increase in speed.

    Just wait until the Sept MBP update, and we'll find out once and for all, if SR can support 800Mhz, because by then 800Mhz DD2 SODIMM should cost almost the same as 667Mhz mem. If the FSB running at 800Mhz makes the system a tad faster, gets you more bandwidth (as the C2D CPU is supposedly limited by the FSB bandwidth), then 800Mhz mem should likewise provide a small boost in speed. But then all manufacturers will probably be using 800Mhz DDR2 RAM, end of debate.

    It's already been confirmed that the DDR2 800Mhz SODIMM's, are running at 800Mhz (not 667Mhz) on Lenovo T61 Thinkpads, somewhere in these former threads I've posted a link to the thinkpad forums where there was heated debate on this. Moreover, all of the system buses can apparently be 'over-clocked' or adjusted, as prior threads I've posted, and posted on, show this to be the case with PC manufacturers like Dell & MSI. In fact Core Extreme 2 rumored to come out at 2.6Ghz in July, and then 2.8Ghz in Sept. are Intel sanctioned CPU's designed with gamer/high-end laptops for specifically overclocking with 'unlocked' frequencies (do a search, you'll find Intel spokespeople affirming this), though MSI seems to have done with with a standard C2D Merom, in as an yet unexplained way.
     
  25. Episteme macrumors regular

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    #25
    The original posted asked why his MBP shipped with 667MHz RAM. The answer is because that's what is officially supported by Intel.

    Intel's current data sheet - dated May 1st, just days before Santa Rosa's official launch list the memory controller as being able to run at 553MHz or 667MHz.

    Anything else is running out of spec and not officially supported by Intel.

    I read a Thinkpad thread on a ThinkPad fan site a few days, and I said at the time, wouldn't call this confirmed. I'd call it claimed. If that's the thread you're referring to, I remain unconvinced. It was one person who insisted it worked but posted no proof beyond insisting it worked for him and got rude with anyone who suggested otherwise. No posters corroborating, no respected tech sites that have made a similar claim, as far as I know.

    I'm afraid I've been around the 'net long enough that I require more than a single person's word it works.

    The other question I have is if the MCH in SR can use 800MHz DDR without issue, why is it absent from Intel's data sheets?

    Almost any computer bus on any system can be overclocked, but what does that have to do with anything? I don't see Apple shipping a system like this out of spec.

    I'm well aware of the X7800/X7900 processors coming soon -- and they're not rumors but have been on official Intel roadmaps for months -- but what do they have to do with the memory controller?

    Intel's made unlocked Extreme Edition CPUs for years. They're poor value, especially when the T7800 launches at the same time as X7900 anyway...
     

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