Originally Posted by Mfusick
81<85<87 The higher the better.
Normally I let my typos go uncorrected because I am lazy but in this case... I need to make the point.
AnandTech had a good memory article recently:
By order of performance or importance:
1. Amount of memory
2. Number of sticks of memory
3. Placement of those sticks in the motherboard
4. The MHz of the memory
5. If XMP/AMP is enabled
6. The subtimings of the memory
I use this order on the basis that point 1 is more important than point 3:
A system will be slow due to lack of memory before the speed of the memory is an issue (point 1)
In order to take advantage of the number of memory channels of the CPU we must have a number of sticks that have a factor of the memory channels (point 2), known as dual channel/tri channel/quad channel.
In order to ensure that we have dual (or tri/quad) channel operation these sticks need to be in the right slots of the motherboard – most motherboards support two DIMM slots per channel and we need at least one memory stick for each channel
If the MHz of the memory is more than CPU is rated for (1333, 1600, 1866+), then the user needs to apply XMP/AMP in order to benefit from the additional speed. Otherwise the system will run at the CPU defaults.
Subtimings, such as tCL, are used in conjunction with the MHz to provide the overall picture when it comes to performance.
So ideally you want to make sure you have "enough" memory before you worry about anything else. Once that is done - You worry about running dual channel (2 sticks) and making sure they are in the right slots (usually slot 2 and 4) and that dual channel gets engaged. You can't run dual channel with a single stick of 4GB or 8GB. You need two of them, and they must be in the right slots and the sticks must be identical.
Once your situated on that aspect- then you can worry about mhz, and then CAS timings.
The interesting point is that low timings does yield some improvement- and as such a CAS 7 or CAS9 subtiming it going to outperform a 10 or 11 all the time. Most "fast" RAM also has a higher sub timing- but when you use that exact same ram at slower speeds (like 1333 or 1600) you can really tighten up the timings. So buying a faster RAM even with a 1333 CPU/Board might allow you to run that 1866mhz or 2400mhz ram at a much lower (faster) subtiming.
Once you start worrying about this stuff you really should be looking at the enthusiast board, and likely your going to get sucked in which takes you out of "budget" territory and into enthusiast terrirotry. You will be rewarded with better performance- but also a lighter wallet. If you don't need it- or if you do is the choice you need to make up front.
Give this a read:
My HTPC is a 3570k. I had Gskill Trident X 2400mhz RAM (8GB with 2 sticks of 4GB in dual channel) installed originally. The ram was very good by the standards of the time (2400mhz is much more common today). I got excellent GPU performance by my HTPC, and I could even run SVP on level 4G (hard to do) and I got pretty decent MadVR performance.
I removed that RAM and installed it into my desktop (4770k on Z87) and put in some 1600mhz Gskill (also 8GB of 2 sticks of 4GB in dual channel) and while my HTPC is plenty fast and ram is not a problem, the one area I can noticed the change is in the integrated iGPU. The slower ram does not lend itself as well to integrated graphics. Adding a video card can quickly solve all that (there is a reason why "real" video cards come with 2GB+ of 256-bit GDDR5 memory and it's not because it's cheaper
That is also why more RAM is better these days if you are on iGPU. You are going to share RAM with video - so if you only go 4GB and you normally would need 2-3GB for windows, and possibly another 1-2GB for video then you are hitting a wall without only 4GB where the performance penalty will show greater than anything else- even if you have ultra fast high end memory. That's why 8GB is getting more common with machines these days, because more and more machines are using iGPU and the iGPU is getting better and better (and more sensitive to RAM quality, speed and amount)
Circling back around,
You are still stuck at the cross roads- do you want a "cheap" value oriented HTPC build that will only do simply playback of movies and tv shows ? If so- slow ram and a pentium CPU is "enough" and so is 4GB. If you might want to do some advanced video rendering for better PQ, play some games or do more advanced things (photoshop loves RAM) you should consider first upgrading to 8GB, second making sure you have dual channel kit and third you likely want 1866mhz ram or greater. (1866 is nearly as cheap and the "value" sweet spot )