Two Sets of Memory W/ Different Speeds

I originally built my computer with 3X2gig OCZ 533MHz DDR3 1066 (I'll admit I was strapped for cash, and found them on sale)

I have some extra cash for Christmas, and wanted to upgrade.

I have 6 slots, Should i bother purchasing higher speed memory?
(Or will the sets only run at the lowest common denominator?)

I run Virtual Machines, and each VM takes 2.5gigs (Each window is running a game inside) I'm not entirely sure if faster memory will help significantly, but I was told more memory would be greatly beneficial to run more then 2 windows. (I currently run 2 (at 2g each), and want to expand to 4-5 at 2.5 each to run the game smoother within the window)

Appreciate it! (I apologize if this was asked before, I searched and the difference in previous questions compared to this is this concerns two entire SETS of 3, not intra-set.)
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  1. Welcome Newcomer. Faster 'timing' is better; not higher frequency, especially if you're not overclocking the RAM. In your specific scenario, you would most certainly benefit from more density (GB). However, occupying all six slots will likely require you to increase the DRAM voltage by ~.1V-.2V. So determine the max voltage you can operate your RAM, in relation to your CPU. For example, the i-series CPUs from Intel limit the RAM to 1.65V for safe operation. Though the voltage can be raised higher, it isn't recommended.
  2. I appreciate the reply.

    I have an I7920 with a (decent) EVGA Mobo. Increasing the voltage slightly wouldnt be difficult.
    You are 100% Correct in the assumption I will not overclock. I run this computer non-stop all day / night, 24/7/365, so overclocking might cause problems

    This is what I'm looking at purchasing

    Would my system be able to utilize the 1600 faster timing (I would put these in slots 1-3-5, the 1066 would be pushed to 2-4-6 slots.


    (I assume the DRAM Voltage modification is in the BIO's, Is there an easy way to check that this is increase-able ? )

    I looked and they are all set at 1.52 (Confirmed) V Currently, so increasing to 1.6-1.62 seems reasonable if I install 3 more slots, I like to stay on the safe side
  3. Best answer
    I think you may have misunderstood my reply. I'll explain a little better...

    The timing is represented like: CL9 or 9-9-9-25

    The frequency is the "rated" speed of the RAM FSB. DDR is double data rate. So, let's take the Memory Clock of the 1600, which is 200MHz. Doubling this would result in 800 MHz bus clock. DDR3 is double of DDR2, so we double it again, resulting with 1600.

    Now to address your question, your CPU can support 1600, but w/o a model number for your mobo, I can't tell you whether or not it supports 1600. Let's say your mobo does support 1600. Using the 1600 and the 1066 would result in you wasting money on the 1600, as they will only operate at 1066. This is because you're mixing the RAM.

    Mixing RAM is not recommended, as it results in poor performance. You are limited to the lower frequency of the mixutre; the slower (looser) timings; and will have to ensure that both sets can operate at the higher voltage.

    For example:

    1600 with CL9 @ 1.5 V and 1066 with CL8 @ 1.6V

    If using a mixture like this you would be forced to use the 1600 (which is likely 1333 stock) at 1066. Your timings will have to be set to CL9, and your RAM would have to operate at 1.6V.

    DRAM voltage is in the BIOS (Basic Input/Output System), along with the timings and frequency settings.

    I strongly recommend that you do not mix 1600 with 1033. Instead, pickup another kit of the 1066 you already have. Like I mentioned before, raising the frequency (MHz) will not yield substantial returns.
  4. I owe you two levels of thank you!

    First of all for forcing me to look carefully at what I own. It looks like the memory is actually 1600 memory! I just never changed the Bio's to recognize this.

    2nd of all for answering my question perfectly, thank you very much! (I'll proceede to purchase exactly what I already have in the other slots)
  5. Best answer selected by uuhitelance.
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