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Which Memory is Truly The Fastest?

Tags:
  • Memory
  • Latency
  • Bandwidth
  • Corsair Dominator
Last response: in Memory
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September 26, 2014 10:34:49 AM

Let me just start off by saying I read someone's post somewhere claiming that to calculate the amount of real time it takes a memory stick to perform a calculation you take the CAS Latency of it and divide it by the bandwidth(MHz). Assuming this is correct the input delay for CL7/1600Mhz should be 0.004375 seconds. Now what really confuses me about the whole bandwidth deal is the fact that some processors only support a maximum of 1600Mhz, 1866Mhz, or 2133Mhz. Yet a lot of the top dollar Corsair Dominator memory is sporting speeds well beyond that.

Let's just say for example you use DDR4 CL15/2800Mhz memory with a CPU that only supports up to DDR4 2133Mhz memory. The CPU should bottleneck the memory reducing it to an effective speed of CL15/2133Mhz. That's quite a substantial slow down according to the earlier mentioned formula.

What would have been CL15/2800Mhz with a delay of 0.005357~second delay has been scaled to CL15/2133Mhz with a delay of 0.007032~second delay.

However, what's more concerning that this is the fact that according to this formula even the standard DDR3 CL7/1600Mhz memory has less delay than this "technological advancement" in the memory department. Now I wouldn't be surprised if higher bandwith had some use in other applications, but in gaming it's all about raw input delay is it not? Then again everything I've just stated could be wrong. If anyone knows the truth of the matter feel free to correct me.

The main question here is really just..

What CL to Mhz ratio is optimal for gaming, without factoring in price, and why?

More about : memory fastest

a b } Memory
September 26, 2014 10:41:07 AM

No bandwidth is better look at gaming benchmarks higher bandwidth results in better fps especially with has well CPUs. The delay of cas latency isn't all that important you want more throughput a fraction of a second difference in response time isn't noticeable at all. Look at ddr4 its cas latency is 15 and up yet it way out preforms ddr3
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September 26, 2014 10:48:52 AM

It may get a few more FPS here and there, but in competitive shooters a fraction of a second can make all the difference between victory and defeat. All I'm interested in is raw delay reduction. A DDR4 rig isn't even within my price range yet anyways. So what would be the best in that regard for DDR3? Unless I've been misinformed it would seem CL7 1600Mhz is the best.
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a b } Memory
September 26, 2014 10:56:33 AM

firo40 said:
No bandwidth is better look at gaming benchmarks higher bandwidth results in better fps especially with has well CPUs. The delay of cas latency isn't all that important you want more throughput a fraction of a second difference in response time isn't noticeable at all. Look at ddr4 its cas latency is 15 and up yet it way out preforms ddr3


But is it? I've read a few articles saying otherwise. That, DDR4 is only marginally better than DDR3, right now. They do imply that it will get better but the first supplier's benchmarks weren't anything to loose your wig over.
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a b } Memory
September 26, 2014 11:07:26 AM

depending on what your board can handle

time to read the first word
1600mhz CAS7 8.75ns
2133mhz CAS9 8.44ns
2400mhz CAS10 8.33ns


I would look for a set of 2133 CAS9 or 2400 CAS10, the higher Mhz will be a lot faster then the 1600mhz

to calculate the cycle time of ram, will take your 1600mhz for example
1/1600 = 0.000625 seconds or .625ns (nanoseconds) that gets you the bit time
to get cycle time 2*bit time so 2*.625 = 1.250ns
First word = ( (CAS latency*2) + (1-1) ) * Bit time so ( ( 7*2) + (1-1) ) * .625 = 8.75ns for the first word


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September 26, 2014 11:15:01 AM

faalin said:
depending on what your board can handle

time to read the first word
1600mhz CAS7 8.75ns
2133mhz CAS9 8.44ns
2400mhz CAS10 8.33ns


I would look for a set of 2133 CAS9 or 2400 CAS10, the higher Mhz will be a lot faster then the 1600mhz


Even if the board can handle it, but the CPU can only handle 1600Mhz max it will still bottleneck though, right?
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a c 2285 } Memory
September 26, 2014 11:23:54 AM

From 1600, high performance DRAM is normally considered 1600/7 1866/8 2133/9 2400/10 and each step up provides a bit of a performance increase that can be seen slightly in gaming (a few FPS) but more so in multi-tasking, etc....In gaming, DRAM is primarily just a data conduit
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