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Ram upgrade - Compatibility question

  • Memory
  • RAM
  • Compatibility
Last response: in Memory
April 19, 2011 4:58:58 PM

I need to upgrade my memory. I have 2 x 1gb of PC2-6400u 666mhz at the moment. Motherboard is a Gigabyte GA-G31MF-S2 Socket 775. I'm looking to get another 2gb in one chip but my current memory is 666mhz and the new memory is all 800mhz so will it be compatible?

P.s. I got the mobo spec here: . It says the following on ram:

1. 4 x 1.8V DDR2 DIMM sockets supporting up to 4 GB of system memory
2. Dual channel memory architecture
3. Support for DDR2 1066(O.C.)/800/667 MHz memory modules

* Because of chipset limitations, do not populate both DIMM sockets of the same channel (e.g. DDRII1 and DDRII2), or populate 4 DIMM sockets with double-sided memory modules to prevent system's failure to start or incorrect detection of memory modules. Please refer to the user manual for the memory configurations table.

* Because of chipset limitations, when using FSB 1333 MHz CPU with populating all DIMM sockets, memory frequency will be reduced from the original, and system instability or incorrect detection of memory module may be occur.
Please refer "Memory Support List" for memory support information.

So this means you can't use all the ram slots of the mobo?

More about : ram upgrade compatibility question

a b } Memory
April 19, 2011 5:42:38 PM

To address the first asterisk, users are being warned not to populate both sockets of one channel OR all four DIMMs WITH double-sided modules. This means that if you choose to populate both slots of one channel or all four slots, you should use single-sided RAM.

The second asterisk is explaining that because of the CPU chipset limitations, use of RAM at a frequency higher than 1333 MHz could cause instability.

So, what does this mean? It means that if you want to use dual-channel RAM, then you must use only two sticks and install them like this: | _ | _ or _ | _ |, and make sure that you don't OC your RAM higher than 1333 MHz.
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April 22, 2011 3:25:59 PM

Thanks for explaining. So does this mean that with the current configuration (2 x 1gb sticks) I will have to remove one stick to add more ram? I'm having trouble understanding why they would add 4 slots to the mobo.

April 22, 2011 3:32:36 PM

Actually I get it, you can use all 4 slots with single channel. So will 1x 666mhz work with 1x 800mhz chip?
a b } Memory
April 22, 2011 5:40:00 PM

There is no guarantee that any combination of RAM will work, even if the RAM is brand new. That being said, it is generally not a good idea to mix RAM because the mixture would be limited to:

1. The lowest frequency (MHz) in common with all sticks
2. The loosest timing (X-X-X-X) in common with all sticks
3. The highest voltage in common with all sticks

You may get the computer to boot; however, you will also likely encounter BSOD and other memory-related failures.

When mixing RAM, a lot of people typically experience the following:

Blue Screen of Death (BSOD) - A Windows Stop Error with some text explaining a possible solution to the error and a code that looks similar to this: 0x000000 (the zeros could be any letter or number)

Unusable RAM - Sometimes with mixed RAM, you may have installed XGB, but Windows will only use XGB (Where "X" could be any value). For example, if you install 4GB of mixed RAM, Windows may only report 2GB usable.

April 22, 2011 11:18:10 PM

Well I just ordered 2gb of 800mhz so lucky me, will hope for the best. If the worst comes to the worst I just fall back to 2gb I suppose, this time 800mhz instead of 666mhz. Then sell existing sticks and buy more.