Can you put 1600 Mhz RAM in 1066/800 Mhz RAM Slot – NO It Might not work!

By | December 1, 2022

If you are upgrading an old PC that has DDR3 1066/800 Mhz RAM slots on its motherboard and planning to upgrade, then you might not be able to find new RAM modules with that frequency.

Newer RAM modules available in the market will have higher frequency like 1333 Mhz and 1600Mhz.

So can you put a 1600 Mhz RAM module in a slot that supports only 1066/800 Mhz RAM modules.

Theoretically it is supposed to work. The RAM stick should simply run at the lower clock frequency.

However the answer is not that simple. There is no guarantee that it will work.

I recently upgraded my old pc which had a Gigabyte GA-G41MT-ES2L (rev. 1.0) motherboard. More details here:

As can be seen on the specs page, it supported only DDR3 1066/800 MHz memory modules.

1. 1600 Mhz RAM - Did not work

I installed a 1600 Mhz memory module, and it did not work.

The exact model was

Hynix 4GB PC3-12800 DDR3-1600MHz desktop 240-Pin DIMM RAM Memory Module Mfr P/N HMT451U6AFR8C-PB

The sticker on the module has the following printed on it:

Hynix / KOREA 05
4GB 1Rx8 PC3-12800U-11-12-A1 

Its a single rank memory.

The number 12800 indicates that its a 1600 Mhz DIMM module. That number is usually indicated on a sticker on the RAM stick itsel or the case.
Divide the number by 8 to get the speed in Mhz.

May be the newest 1600 Mhz don't support running at lower clock speeds so they are less likely to work. The 1600 Mhz RAM can be identified by the number

2. 1333 Mhz RAM - Did Work

After that I purchased another memory module with 1333 Mhz frequency and put that and it WORKED!!.

The exact model is:

Hynix 1333Mhz Desktop PC RAM DDR3 4 GB (Dual Channel) PC (HMT351UCFR8C-H9 PC3 10600U)

The number 10600 indicates that its 1333 Mhz

So the answer is that 1600 Mhz memory modules may not work in a slot that supports only upto 1066 Mhz. However the 1333 Mhz RAM worked.


If higher frequency RAM modules are installed in lower frequency slots, their speed is stepped down to match that of the slot and the system uses them as usual.

But this does not happen always. If the RAM module does not support stepping down the frequency

So if you are planning to buy some RAM for your old PC, keep in mind that it might not work.

You are better off trying a 1333 Mhz RAM instead and it is more likely to work.

Though a 1600 Mhz RAM might work, but there is no guarantee.

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About Silver Moon

A Tech Enthusiast, Blogger, Linux Fan and a Software Developer. Writes about Computer hardware, Linux and Open Source software and coding in Python, Php and Javascript. He can be reached at [email protected].


Can you put 1600 Mhz RAM in 1066/800 Mhz RAM Slot – NO It Might not work!
  1. Edu

    You are wrong in your conclusions, the reason some rams work and other not is not the speed, 1600mhz ram will always work on a 1066mhz motherboard.
    The thing is you motherboard need 2rx8 ram modules instead of 1rx8.
    The first model you posted that didn’t work is 1rx8, the second one is 2rx8.
    Basically this menas the module must have chips on both sides (2rx8) instead of only one side (1rx8).
    That’s all

    1. Silver Moon Post author

      the first ram that i tried (1600 Mhz) is indeed a single rank module.

      how do you know that motherboard works only with dual rank ram ?
      where is that information found ? i could not find anything in the specs online.

  2. Josh

    Hey bro… thank you so much for the information. Just a query
    My old all in one pc from hp purchased in 2012 has a ddr3 2gb ram (1067 speed) with intel celeron 1.6ghz or 1600 ghz. Can I upgrade it to 2 x 4 ddr3 ram of 1333ghz? By the way my windows has already come to an end of life so even new updates are not taking place anymore.
    If try to update, the system first initializes then downloads and finally freezes forcing me to shut down the power switch. By the time I reopen my system “undoing changes made to your system” apears.

  3. Anubhav Dutta

    Thanks for the article bro.. loved reading it and was actually looking for some article like this one. I just recently happened to upgrade RAM in my HP laptop.
    The upgrade was inserting an additional memory in the unused 2nd RAM slot. Inserting a higher frequency ram to a lower frequency slot, that was on my 7 year old HP Sleekbook 14 which has a 2nd gen core i-3, supporting only 1333Mhz. The 1st slot already had a 4-GB 1333Mhz DDR3L stick installed since beginning while I plugged in an additional 4-GB 1600Mhz DDR3L (of Silicon Power brand). The higher frequency 1600 ram downclocked to 1333 and is working fine. The command prompt window shows both the RAMs at 1333 Mhz speed. Also read the service manual, which reads as “DDR3-1333 MHz support (DDR3-1600/DDR3L-1600 downgrade to DDR3-1333), for use with computer models with 2ndGeneration Intel Core, Pentium, or Celeron processors”

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