2133Mhz dual channel vs 2400Mhz single channel

[wii1990]

So I currently am running a A10-5800 APU with 8GB 1866mhz ram and a GTX 260 core216(http://www.newegg.com/Product/Product.aspx?Item=N82E16814130433) and I'm deciding to upgrade. I'm looking at getting an A10-7870 APU and this motherboard(http://www.newegg.com/Product/Product.aspx?Item=N82E16813132255). AMD states that the AMP 2400 speed profiles only work in single dimm per channel(http://www.radeonmemory.com/gamer_series.php under features tab). So my question is, using the APU for graphics until I get a dx11/12 GPU, would 2400Mhz ram one per channel or 2133Mhz ram in dual channel gave better performance, or does it matter?

 

[jtabb1256]

Copied and pasted from:
http://www.pvladov.com/2013/01/improve-intel-hd-graphics-performance.html

"Increase the amount of RAM and make it work in dual channel mode
Integrated graphics cards usually do not have their own memory (or only have a small amount of one). They take memory from the RAM of the computer. When your computer has more RAM the Intel HD Graphics will be able to utilize more memory. But what will really speed it up will be using two memory sticks of the same capacity and speed. In this case you computer's RAM will begin to work in dual channel mode which means that it will become at least 15% faster. As the integrated graphics use computer's RAM extensively you can expect an even greater performance improvement for your Intel HD Graphics - it will become 20 - 25% faster in most applications and games."

This is talking about intel hd graphics, not the amd apu, but the same concept applies. If this "15%" factor is true, then dual channel will give you much better performance than the slight increase from 2133mhz to 2400mhz.

 

[bootcher]

I think you are mixing two different things. 2400 mhz will only work with one single ram stick per channel. This still means it will work in dual channel if you have two sticks of 2400 mhz ram. 2400 mhz ram will not work of there are two sticks per channel, which would be a 4 ram sticks setup.

Other than that, the speed of 2400 versus 2133 will largely depend on the cas latency of the ram. 2133 mhz cas 11 will be faster than 2400 cas 13 memory.
for example (CAS / Frequency (MHz)) × 1000 = X ns)
2133 cas 11:
11/2133x1000=5.157 ns
2400 cas 13:
13/2400x1000=5.4166 ns
(shorter is faster)

 

[jtabb1256]

I think you are mixing two different things. 2400 mhz will only work with one single ram stick per channel. This still means it will work in dual channel if you have two sticks of 2400 mhz ram. 2400 mhz ram will not work of there are two sticks per channel, which would be a 4 ram sticks setup.

Other than that, the speed of 2400 versus 2133 will largely depend on the cas latency of the ram. 2133 mhz cas 11 will be faster than 2400 cas 13 memory.
for example (CAS / Frequency (MHz)) × 1000 = X ns)
2133 cas 11:
11/2133x1000=5.157 ns
2400 cas 13:
13/2400x1000=5.4166 ns
(shorter is faster)

ctrl + f this : " *2400MHz supported with 1DPC (DIMM per Channel) - Max. 2 DIMMs per PC system"
in his link under the features tab

Nevermind. I see that you addressed this. Can the memory controller really work in dull channel mode if it is using one stick from one channel and another stick in another channel?

 

[bootcher]

Yes, dual channel requires exactly what you describe, at least 1 stick per channel. In the case of 2400mhz it is also the maximum amount of stick per channel to enable dual channel.

 

[Tradesman1]

Yes, dual channel requires exactly what you describe, at least 1 stick per channel. In the case of 2400mhz it is also the maximum amount of stick per channel to enable dual channel.

____________________

In single channel mode the MC (memory controller) sees the DRAM as a 64bit device, when indual channel mode be it 1 stick in each channel or 2 in each channel the MC sees it all as a single 128bit device, which is where you pick up the performance increase (on AMD rigs it can be upwards of 10% or so), along with the performance increase to the iGPU from the more and faster DRAM 😉

 

[jtabb1256]

Yes, dual channel requires exactly what you describe, at least 1 stick per channel. In the case of 2400mhz it is also the maximum amount of stick per channel to enable dual channel.

____________________

In single channel mode the MC (memory controller) sees the DRAM as a 64bit device, when indual channel mode be it 1 stick in each channel or 2 in each channel the MC sees it all as a single 128bit device, which is where you pick up the performance increase (on AMD rigs it can be upwards of 10% or so), along with the performance increase to the iGPU from the more and faster DRAM 😉

I thought dual channel was when 2 sticks were in the same channel. Am I misleaded by the coloration on the motherboard? Is one channel really 2 slots that are side by side and so the motherboard has alternated colors of ram slots so that the user puts one stick in each channel (a channel meaning two slots that are side by side instead of what I previously thought of as a channel, which is the slots that match in color)?

 

[Tradesman1]

Yes, on most mobos that have 4 slots Channel A will be the 2 slots closet to the CPU and channel B will be the two furthest away (3-4) slots 1-3 (A1-B1) are normally one color while (A2 and B2) are a different color to let you see the options for dual channel slot set up