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I'm getting a new PC soon and I've been looking at CPU and RAM options then realized that maybe my HD is my bottleneck.

Is there an easy way to figure out which component is the biggest bottleneck?

I found one article on this explaining how to use the Windows Performance Monitor but then you have to wade through the measurements and make some educated decision.

I'm looking for an idiot light that says "HD=bottleneck"

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You're most likely asking about system responsiveness, which would be how quickly it reacts to your user input, such as double-clicking to open a program or switching between programs.

The two easiest ways to increase system responsiveness are:

  1. Faster hard drive
  2. More RAM

The hard drive is by far the slowest system component. If you put in a 10,000 RPM hard drive or high-quality SSD drive, you'll significantly reduce the latency to fetch data from the drive, resulting in programs opening faster.

More RAM allows more applications to run at the same time. Windows Vista and 7 also use RAM as a cache. RAM is the single cheapest way to improve system performance.

In general, the CPU is never the limiting factor (except for gaming or video encoding). You can get by just fine with a decent dual core for most everyday usage (like the Athlon II).

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up vote 4 down vote accepted
  1. Article on the Performance Monitor in Windows XP. However, The Process Explorer, below, does a lot of that for you.

  2. And SysInternals Process Explorer (now owned by Microsoft) is a great simple tool for measuring a lot of this. It'll show % of max utilization for CPU, RAM, etc as well as showing peak and showing a running graph.

    The fellow who created it (blanking on his name) keeps it running and then when (not if :-) his PC slows down, he looks over at the graph to see what what the bottleneck is (RAM, CPU, HD, etc.) and then what app is the biggest load of that resource.

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SysInternals guys are Bryce Cogswell and Mark Russinovich. I recommend any SysInternals tools. – Doug Harris Dec 17 '09 at 23:50

Here's the Idiot's Guide to PC Bottlenecks, Short Version. You can safely assume that due to the laws of physics and the engineering of the modern PC, this is it for application-agnostic bottlenecks.

Generic PC components, from slowest to fastest:

  • USB-1
  • Optical drive
  • Network (wireless)
  • Network (wired)
  • USB-2, Firewire
  • Hard drive (std, IDE)
  • Network (wired, gigabit+)
  • Hard drive (std, SATA-II)
  • Hard drive (SSD)
  • GPU, RAM, system bus
  • CPU

Now, any of them can be "the" bottleneck for a certain application or system configuration. If your application is slower than you think it should be, you have to consider everything about the PC to find the problem.

That's when benchmarks and measurements come into play, and things get complicated. Without knowing what application you're optimizing a PC build for, you can't optimize properly.

If all you want is to max out your hard drive speed, buy an SSD drive to go with whatever CPU/RAM/motherboard combination you decide on.

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The fact is that there will never be an "idiot light" that tells you what your bottleneck is because it's completely dependent on exactly what you're doing at the time, and can even vary a lot during different parts of the same general task.

If you could be more specific with exactly what your typical usage consists of, people may be able to give general recommendations.

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What I'm looking for is (ideally software that provides) feedback on what my bottleneck is during a given period of time. So I could note "my PC was really slow for 2 minutes there, what was the bottleneck during that period. – Clay Nichols Oct 25 '09 at 15:15

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