I am wanting to upgrade my RAM on my Gigabyte P31-DS3L. Currently I have 2x1GB XMS2 Corsair 6400 RAM running in dual channel configuration. I was hoping to just buy another 2x1GB sticks but after a peruse of the manual (page 16), it says: "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." and "Memory configurations below [showing all 4 memory slots being used with single-sided RAM] will result in memory frequency being reduced from the original frequency. So am I to understand that I can't run dual channel memory with 4xRAM sticks? Would I lose much performance by just running 4 single channel sticks, or would it really be a big performance hit from running 2x2GB sticks? It would cost close to £100 to get that and then I'd also have 2GB of useless memory... Forgive my ignorance, I really don't know too much about RAM
All they've done is make it sound confusing for the hell of it. DDR3 boards natively run at 1333mhz, so if you've got 1333mhz then nothing will change, but if you fill it with 1600mhz for example, it will default back to 1333mhz. DDR2 is the same with an 800mhz default. Now if you want to go for high speed ram in all 4 slot then you'll have to have a fiddle with the settings but it's not hard. I'm running 1066mhz with an overclock and it rock solid. The other choice you've got is to get rid of the 2Gb and by 4Gb sticks and n ot have to worry about anything. If you want to add 2GB and fill all 4 slots you wont have any problems.
yeah, no worries. it just means that if you use a CPU with a FSB (front side bus, the speed at which your cpu communicates with the motherboard) of 1333mhz (most every cpu that fit in your board have a FSB of 1333mhz) the ram will adapt to that speed and will operate at that frequency, even if you buy 1600mhz ram. if you put in 1333mhz ram, nothing will be reduced.
Ah okay. The CPU is an Intel Dual Core (not C2D) E2220 @ 2.4 GHz (currently OC'd at 2.8GHz - I'm working on this ). The RAM I currently have is 6400 (so I guess this is 800MHz). So basically, if I add in another 2 sticks i.e. 4x1GB, then they will still be running in dual channel? Thanks.
They will run in dual channel but you may have to drop the speed from 800MHz down to 667MHz to run all 4 sticks. This is a common problem and is a limitation of of a lot of motherboards. Each 6400 stick will run at 400, having two of them (dual channel) makes it 800. However, you might have to run each stick at 333 to get 667 dual channel.
Ah so, in terms of performance I shouldn't really see a decrease? Is changing the speed they run at simply a matter of changing the ratio or FSB in the BIOS á la Overclocking the CPU?
No, changing the RAM speed isn't anything to do with the FSB speed unless you keep them linked in the BIOS. Generally you want to unlink the FSB from the RAM speeds and manually set them. Basically the reason the limitation is there is because the memory controller cannot supply enough grunt to run all four slots at the highest rated speed. I am not sure you will see the difference between 667 and 800 speed RAM in every day use. Edit: I have just read the spec of your motherboard. It says it can run 1066 RAM so you might actually be fine running all four sticks at 800. Give it a try and see how you go. If your RAM is CM2X1024-6400C4PRO then it is on the memory compatibility list for that motherboard. However, these are double sided modules and Gigabyte do say, as you pointed out, that you should only run single sided modules when filling all four slots. If it was me, I would try it and see. If it doesn't boot then you know the answer.
You will also have problems if you populate all slots with DIMM's. I had a lot of POST probs with my Asrock 4CORE 1600-GLAN when I tried a 4 x 1GB DIMM's. It either wouldn't get past any POST or would reduce each DIMM to 512KB. All 4 slots will have to be SIMM's.
