Single stick of ram

[ironmask]

I have a noob questions. I have 16 gb ram right now-- 2x8. If I go down to a single channel at 1x8, does that decrease my ram speed from 1600 to 800? I'm just curious and would like an understanding.

 

[_Rick_]

You can use synthetic memory benchmarks to see what the worst case decrease in performance is. It could in theory be up to 50%.
But the actual rated speed of each stick is in no way impacted.
RAM throughout in MB/s will go down, how much depends on the memory controller.
How much you'll actually feel it in applications depends on how much cache your CPU has, and how your binaries are compiled, and what kind of problems you're treating.
There are few RAM-streaming applications in the consumer space.

 

[tweakboy]

You will get 1 lane of data passing through.

You probably wont feel a difference.

go 8x2GB 2 and 2 on mobo..

 

[G73S]

I have a noob questions. I have 16 gb ram right now-- 2x8. If I go down to a single channel at 1x8, does that decrease my ram speed from 1600 to 800? I'm just curious and would like an understanding.

you're right. It's called DDR (Double Data Rate) for a reason. Always keep them in matching pairs or you are decreasing your bandwidth of the RAM channel by half.

 

[Topweasel]

you're right. It's called DDR (Double Data Rate) for a reason. Always keep them in matching pairs or you are decreasing your bandwidth of the RAM channel by half.

That's not why it's called DDR, double data rate means that it can send out two packets of information per clock cycle. So a 800Mhz chip is in reality a 400MHz chip that is sending packets of information like it was really a 800MHz chip. Which makes the whole DDR portion kind of redundant. It's either DDR 400MHz or 800. But that is just me nitpicking naming.

Anyways. Most controllers in the last 10 years whether internal or external have been "dual channel" controllers. Usually with 4 memory slots. So it's recommended that they be installed in pairs. This is to make the 64bit bus into a 128bit bus and doubling memory throughput. On a DDR3 1600, a single chip will have 10GBs bandwidth. So 20GBs with two chips. In most systems (gaming systems) the only thing that would need even close to 10GBs a second for system memory access would be a video card. PCIe 16x 3.0 has 15.7GBs of bandwidth. In that sense depending on the video card in use you could see a 33% drop in performance compared to other systems when the video card is retrieving information from system memory.

But that's just a numbers comparison. It's hard to tell what cards would even come close to that. Generally the spec is updated 2-3 times before a card would ever come close to needing the bandwidth. I know the Titan did like more than PCIe 8x 3.0. But I couldn't tell you if needs more than 10GBs. I also couldn't tell you that even if you had a card that desired that kind of system memory bandwidth how much it would truly affect game performance.

That said DDR3 memory is unlikely to get any cheaper and I think most people will be doing themselves a disservice by not getting and keeping their eventual target amount now instead of waiting till 2015 when DDR4 is released and DDR3 gets scaled back even more and starts increasing in price.

 

[ironmask]

That's not why it's called DDR, double data rate means that it can send out two packets of information per clock cycle. So a 800Mhz chip is in reality a 400MHz chip that is sending packets of information like it was really a 800MHz chip. Which makes the whole DDR portion kind of redundant. It's either DDR 400MHz or 800. But that is just me nitpicking naming.

Anyways. Most controllers in the last 10 years whether internal or external have been "dual channel" controllers. Usually with 4 memory slots. So it's recommended that they be installed in pairs. This is to make the 64bit bus into a 128bit bus and doubling memory throughput. On a DDR3 1600, a single chip will have 10GBs bandwidth. So 20GBs with two chips. In most systems (gaming systems) the only thing that would need even close to 10GBs a second for system memory access would be a video card. PCIe 16x 3.0 has 15.7GBs of bandwidth. In that sense depending on the video card in use you could see a 33% drop in performance compared to other systems when the video card is retrieving information from system memory.

But that's just a numbers comparison. It's hard to tell what cards would even come close to that. Generally the spec is updated 2-3 times before a card would ever come close to needing the bandwidth. I know the Titan did like more than PCIe 8x 3.0. But I couldn't tell you if needs more than 10GBs. I also couldn't tell you that even if you had a card that desired that kind of system memory bandwidth how much it would truly affect game performance.

That said DDR3 memory is unlikely to get any cheaper and I think most people will be doing themselves a disservice by not getting and keeping their eventual target amount now instead of waiting till 2015 when DDR4 is released and DDR3 gets scaled back even more and starts increasing in price.

Thanks! I was just curious. I have 16 now but will be going to 32. I needed to know, because I'll be doing a build for my kids and wondered if I could get away with a single 8gb stick.

 

[Coup27]

I have a noob questions. I have 16 gb ram right now-- 2x8. If I go down to a single channel at 1x8, does that decrease my ram speed from 1600 to 800? I'm just curious and would like an understanding.

A single module will run as fast as 2 modules in a dual channel config. You can buy single 1600Mhz modules or a dual channel kit of 1600Mhz modules, the speed doesn't change whether you use one or two.

Speed of RAM is not the same as bandwidth however.