DDR3-1866 or -2000 on i7 950?

Hi all,

Using an eVGA X58 FTW3 with an i7 950 installed (no OC). Right now it has DDR3-1600 HyperX running in XMP mode but I just saw on the eVGA support page they now support DDR3-1866 and DDR3-2000 on this motherboard.

On my old Core 2 Quad I used to understand how to select the memory speed/FSB ratios for best performance but with the QPI architecture that's all different now. I've not kept up with it, sadly.

Intel's website says: "These processors support DDR3 memory with a maximum frequency of 1066 MHz. If faster DDR3 memory is used (such as 1333 MHz or 1600 MHz), it will be down-clocked to operate at 1066 MHz."

Is there going to be any performance gain with this faster memory? I'm guessing I will need to overclock to let it use the higher speeds, unless XMP is doing that for me automatically. Just doing light gaming and web surfing. Again I am unclear on how the QPI stuff works with memory speeds and ratios. Thanks in advance.

On my old Core 2 Quad I used to understand how to select the memory speed/FSB ratios

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There is not really any such thing any more with integrated memory controllers. What I mean is you do not want or use 1:1 any more. There is no FSB although BCLK can be seen as similar. However that runs at 133 Mhz. Also this is a bit of installing memory that is a higher frequency than then memory controller was designed to run at. I am pretty sure your core2 motherboard would not accept 2000 MHz ram either..

s there going to be any performance gain with this faster memory?

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On average not really. However for some applications yes.

I'm guessing I will need to overclock to let it use the higher speeds, unless XMP is doing that for me automatically.

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XMP is about overclocking only the memory controller. Although overclocking the processor can also allow support for this ram. You can also manually set the frequency and possibly give the IMC a voltage bump to work with the overclocked setting.

I hate to discourage new overclockers, but there is little point in overclocking the memory that high. I really don't think it will add that much performance.

You need a chip with a pretty strong IMC and often a hefty amount of vtt voltage to run daily 2000 ddr3 speeds. It get even harder as your overclock increases.

There's really no reason to buy faster RAM than 1600mhz, the price/performance drops dramatically.

If you are going for a mid to high OC, then you will want the 1866 or faster so that you do not have to compromise on memory frequency. OCing memory alone offers minimal gains and you also don't want your memory to be limited to a very low divider when you have a high CPU OC.

So in what instances would I see benefit from faster memory? I'm going to go out on a limb and say the memory and CPU speed are not the limiting factor in my current box, especially for what I do.

The GPU is a 560 GTX Ti 2GB if it matters. I occasionally play BF3, Mass Effect 1/2 (and 3 when it arrives), Crysis 2, and whatever else strikes my fancy. It's a few hours a week recreationally, that's all.

I've done a lot of generic testing over the years. I don't recall the specific breakdown of what apps or types of apps benefit most from memory frequency. But, on average you'll see about a 2% -3-% gain across the board if you OC your memory to 1600 or more vs the stock setting of 1066.

So, if you are leaning towards bang per buck, buy less expensive memory. If you are wanting to squeeze every last single bit of performance from your OCing, get the DDR2000.

dparm said:

Intel's website says: "These processors support DDR3 memory with a maximum frequency of 1066 MHz. If faster DDR3 memory is used (such as 1333 MHz or 1600 MHz), it will be down-clocked to operate at 1066 MHz."

I'm guessing I will need to overclock to let it use the higher speeds?

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There's an override setting for intel limitation in the bios, that allows 1600 to be selectable in the dropdown menu. For higher speeds than that, I'm not sure if it's as easy, but you wouldn't normally notice the difference between 1600 and 2000.

If it was 1600 vs 2400 you could see an actual FPS difference in a game/video benchmark (albeit VERY small, maybe 2fps?) anything less you will literally see nothing in non memory benchmarking applications. It's worthless.

If its not adding more ram, not worth it

The memory speed is just a multiplier against your baseclock. You can select any multiplier you want.
So, for example...
133BCLK with a 6x memory multiplier gives you 798MHz, or 1596MHz DDR.
On the same note, say you switch up to the 7x multiplier:
133x7x2 = 1862

So, 1866MHz is reachable without any overclocking.

To get 200MHz, you must increase your BCLK to 143MHz, which would overclock your CPU slightly.

Also keep in mind that with i7 Bloomfields like yours, getting high memory clocks is difficult due to the 2x UCLK rule.

So, in short... Everything gets more complicated after 1600MHz, but it doesn't get really hairy until 2GHz.

So, 1866MHz is reachable without any overclocking.

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You are still overclocking the memory controller. Remember that the memory controller was designed to run at DDR3 1333 or DDR3 1066 depending on the chip.

You'd probably see better results oc'ing your current RAM to 1866 with looser timings rather than getting new RAM. And as people have already noted there is miniscule benefit to moving from 1600 --> faster RAM, perhaps 4-8% max. I'd recommend an SSD boot drive first if you didn't already have one, and otherwise would recommend saving that money towards other options like video card/new cpu.