How close is an SSD to being as useful as RAM?

Discussion in 'MacBook Pro' started by danpass, Aug 17, 2011.

  1. danpass macrumors 68020


    Jun 27, 2009
    Miami, FL
    I'm not certain how to relate the two, I was just thinking if the whole SSD concept is so fast then the whole page in/page out situation when RAM fills up could be mitigated by having a really fast drive, i.e.: an SSD drive.

    How close is a 7200rpm disk? 10% as fast as typical RAM? 25%

    An SSD? 50% as fast?

    Just wondering.
  2. superericla macrumors 6502

    Sep 27, 2010
    DDR3-1333 RAM can reach speeds of 10667 MB/s while the typical SATA 3 SSD can run at around 550 MB/S. So RAM is basically around 20+ times faster than a typical SSD.
  3. 2hvy4grvty macrumors 6502

    Jun 17, 2011
    SSDs won't replace RAM if that's what you're saying... same reason RAM won't replace CPU cache.
  4. jamisonbaines macrumors regular

    Dec 14, 2007
    Specs aside i have a netbook with OSX and SSD along with 2 GB of RAM and I'll be deep into page outs and rarely ever notice any lag like you would experience with a HDD.

    RAM is cheap enough to jump on 8 GB but if you're choosing between 16 GB or an SSD get the SSD.
  5. jimmie32 macrumors member


    Feb 11, 2011
    Beijing, CN
    As pointed out by 2hvy4grvty, basically,
    L1 Cache > L2 Cache > L3 Cache (Now called Last Level Cache, LLC, by Intel) > RAM (In general here) > SSD > HDD. Of course, you can't get more cache since its built into the processor, but if you are wanting to speed up your computer, changing to a SSD might yield more noticeable day-to-day performance than upgrading RAM.

    This is because, if you get more RAM, you'll only notice it in cases where you have many windows open / heavy multitasking. Sure, I do virtual machining, so 8GB is certainly noticeable once I get my Windows 7 VM open, but if you're just doing some basic work, not a big chunk of difference.

    A SSD is different though. It will make opening apps, saving things, reading things, much faster than a normal hard drive.

    Swap files on SSDs won't replace RAM anytime soon. SSD read/write speeds peak out at ~500MB/s, while RAM could hit ~10GB/s. SSD speeds might go higher, but well, RAM will go higher, too. We won't see a merge anytime soon. :D

    Perhaps we'll see RAM and SSDs merge when Mac and Windows merges. /s

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