4x2GB@1066

[uname]

Can someone help me with this one:

I would like to assembly my new machine on GA-MA790X-UD4 (rev. 1.0) platform.
Also, I would like to buy 8GB of memory and AMD Athlon X2 7750 BE which will later be replaced by some quad core am2+ or am3...

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According to specs this is AM2/AM2+/AM3 capable motherboard.
http://www.gigabyte.com.tw/Pro...ew.aspx?ProductID=3002

AM2+ CPU has limitation and support only two memory modules at 1066. Correct?

*Due to AMD CPU limitation, DDR2 1066 is supported by AM2+ CPU for one DIMM per channel only* from the above link.

So running 4x2GB at speed of 1066MHz is not possible using this (AMD Athlon X2 7750 BE) AM2+ CPU.

Now,

AM3 CPU comes with memory controllers for DDR2 and DDR3.
AM3 is also backwards compatible with AM2+ slot in this motherboard.

Does AM3 CPU inserted into this motherboard support 4x2GB memory configuration at speed of
1066MHz? Does this "one DIMM per channel" limitation applies for AM3 CPU-s as well?

If not, is there any point in getting 4x2GB of DDR2@1066 instead of DDR2@800 beside ability to
overclock by making some space with DDR2@1066 sticks failed back to DDR2@800?

Thank you!

 

[lopri]

Originally posted by: uname

AM2+ CPU has limitation and support only two memory modules at 1066. Correct?

Yes.

Does AM3 CPU inserted into this motherboard support 4x2GB memory configuration at speed of 1066MHz? Does this "one DIMM per channel" limitation applies for AM3 CPU-s as well?

The limitation is same for AM2 and AM3 CPUs. It's a tricky matter but a short answer is that it won't work unless you have the right combination of everything. (good CPU, memory, board, and BIOS) The board you're looking at handles two sticks @DDR2-1066 very well, but not with 4 - it won't boot or it will BSOD if it boots.

It can help if the memory is programmed for DDR2-1066 (be it SPD or EPP) - remember that 99% of DDR2-1066 sticks in the market are overclocked DDR2-800 sticks and usually don't contain proper SPD for DDR2-1066.

If not, is there any point in getting 4x2GB of DDR2@1066 instead of DDR2@800 beside ability to overclock by making some space with DDR2@1066 sticks failed back to DDR2@800?

That depends on many things and frankly the biggest factor used to be $$. But these days there isn't much difference in price between the two so it won't hurt to pick up DDR2-1066 over DDR2-800, all else being equal. Try to find sticks with lowest voltage possible. I'd personally don't go past 2.0V.

 

[uname]

Thank you for your response.

So if I go with 2 4GB sticks instead of 4 2GB sticks this motherboard should work without problems @1066?

 

[lopri]

You won't find 4GB sticks rated DDR2-1066.

You can do 4x2GB 1066MHz if you don't mind overclocking. In your BIOS, you will have several dividers available for memory. You will likely want to use:

2:3 for DDR2-667
1:2 for DDR2-800
3:8 for DDR2-1066

What's difficult is to use 4 sticks and 3:8 ratio. But if you use 1:2 and raise HTT, then you will be able to do 1000MHz+. I was/am not sure whether you're into overclocking so naturally my answer above was based on stock configuration. The 'native' DDR2-1066 on AM2+ is achieved by using 3:8 divider.

2x2GB DDR2-1066 using 3:8 divider

If you raise HTT while using 1:2 divider (or any other), you will raise memory speed proportionately.

4x2GB DDR2-1000 using 1:2 divider

 

[poohbear]

To the OP, has it been demonstrated that there's any performance benefit in real world apps to worry about going from tight ddr2 800 timings to loose ddr2 1066 timings? all the reviews i've seen indicate not at all, so why are u worried about this?

 

[uname]

@poohbear - I am not really a "last MHz / FPS" type of performance junkie so it is more kind of asking to clear some things up before I go out and buy something . Your answer is informative too...

@lopri - thank you again

 

[uname]

@lopri - regarding overclocking - not really into that by default but it is nice to know what should be possible using that ram combination/type/speed if I try...

 

[johnkrog]

Hello I want to ask, if I overclock my P2 940BE but I leave the RAM memory stock (DDR2 800 MHz) what happens? I mean do you need faster memory to benefit from overclocking the CPU? I hope you understand my question.