So I'm building a new machine... Which configuration would give me a faster machine:

  1. 8 Gb of RAM
  2. An SSD, but with 4 Gb of ram

Should I add more memory (8 Gb instead of 4Gb) to better make use of superfetch, or should I invest in a good SSD drive?

  • 1
    I hope you are using 64 bit operating system since you cannot use more than approx. 3.3 GB on 32 bit os.
    – Hemant
    Feb 1, 2010 at 3:50

4 Answers 4


I doubt that RAM is the bottleneck, unless you are running multiple VMs or something like that.

Read/write speeds are most likely the bottleneck on any modern machine, so getting a faster drive is usually the best solution.


I'll let our esteemed Jeff Atwood answer this question. From his post today:

In my humble opinion, $200 - $300 for a SSD is easily the most cost effective performance increase you can buy for a computer of anything remotely resembling recent vintage. Whether you prefer the 80 GB X25-M SSD or the 128 GB Crucial SSD, it's money well invested for people like us who are obsessive about how their computer performs.

Trust me, you will feel the performance difference of a modern SSD in day to day computing. That's far more than I can say for most of today's CPU and memory upgrades. The transition from magnetic storage to solid state storage is nothing less than a breakthrough. It's already transformative; I can only imagine how fast, cheap, and large these drives are going to be in a few years. So, if you've ever wondered what performance would be like if everything was in RAM all the time -- well, we just got one giant step closer to that.


4GB with SSD I doubt you use any programs that would use more. By the way do some reading on Superfetch it sounds like you aren't exactly clear on it.

  • 1
    Not sure what you mean by that. SuperFetch uses excess RAM to cache commonly read files (hence speeding up access). But I would go with SSD anyway.
    – dlux
    Oct 22, 2009 at 21:28
  • Depending on the applications being run you can easily go over 4GB with e.g. firefox + a game. I would go for 8GB + SSD (in fact that's exactly what i've done). User10547 I'm not sure YOU'RE clear on things.
    – frankster
    Jul 20, 2011 at 9:59
  • Well, this answer didn't age well. Feb 8 at 15:52

I would choose 8GB of RAM.

SuperFetch caches in RAM (ram drive) apps you have been using, so it doesnt have to go to SSD or HDD to get them. If you've got 8GB of RAM, Windows 7 uses about 1.2GB to hold the entire OS. That leaves 6.8GB of cache for programs you normally use. Not many people normally use more than 6.8GB of programs. So effectively all your apps are in ram ready to go.

If you gave up that 4GB RAM to get SSD, that means you most likely will have to go to disk for some stuff (e.g. MS Office: 700MB, major game: 1GB).

So now you compare the access speed of RAM vs SSD:

Type  Random Access Time (ns)  Speed (MB/sec)
====  =======================  ==============
RAM                    1       6,800
SSD               100000         200
HDD             20000000          90

It's going be a long time before SSDs make more sense than RAM cache, if ever.

It's a common fallacy that excess RAM is not effectively used in Vista and Win7. It's 100% used for RAM disk and immediately available for user use. Best of both worlds. The best upgrade I ever did was moving from 4 to 8GB of RAM; immediate seat of the pants performance improvement.

The ideal setup is SSD + max RAM; if you can afford it.

  • SuperFetch is great to pre-cache files you will use. But a SSD helps get those program chunks into memory faster; lightening the load on the hard-drive itself.
    – Ian Boyd
    Feb 25, 2011 at 21:08
  • 1
    You would never repeat this experiencing an SSD
    – bortao
    Sep 20, 2011 at 22:25

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