s3anister :
Oh you are so close yet so far to knowing what you're talking about...
You would be well served to learn about the Von Neumann architecture and more precisely the Von Neumann bottleneck.
http://en.wikipedia.org/wiki/Von_Neumann_architecture
The biggest bottleneck in any architecture is shared communication between all components, data throughput is crucial to all parts of a system; yet beyond that
latency of components in relation to bandwidth is the real Achilles heel of the computer and THAT is why CPUs have L1/L2/L3 cache so that they can have ultra low latency memory that is usually around 1.5/5/7.5ns respectively. When you have that low latency combined with a bandwidth of what is 76000/44000/22000 MB/s compared to normal DDR3-1600 on sandy/ivy bridge you have a system that appears to not be bottlenecked by RAM. As for a Trinity AMD system, the reason why one sees such massive gains when going up in RAM speeds from DDR-3 1600 to 2133 is because the GPU can't get away with the tiny amount of storage that is the L1/L2 cache, it has to have a large interface of 512MB-3GB to crunch the massive amount of parallel data and therefore is limited by the aggregate throughput of the system's memory. Hypothetically, if you were to continue to increase the data rate of the system's memory you would see performance gains up until the point where the GPU's instructions units can no longer make use of the available interface.
Having said all that, until DDR-4 is out we can't say for certain that it will not have a huge impact on both AMD and Intel systems. This is because if DDR-4 manages to lower latency or greatly increase bandwidth you will see gains, especially if DDR-4 is able to achieve both lower latency and higher bandwidth at the same time. Oh and, to correct your first inaccuracy, DDR-4 will be lower power than what is currently available so it will use less electricity than DDR3-2400 therefore providing more performance per Watt of energy used.
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The biggest bottleneck in any architecture is shared communication between all components"
I know, but there isn't just one way data travels between components. A "collective bottleneck" is hardly a bottleneck so much as a limitation of the entire system. It's like saying "your system is limited by your system's limitations". PCI-Express for example, is just one specific component, the interface which connects a CPU to its internal caches is another, and so is the component which connects the CPU to the RAM, which was primarily the FSB before CPUs integrated that function on-dye.
What you're saying is that the collective limitations of PCI-Express+internal CPU interface+FSB+SATA+everything-else-I-missed = ONE "bottleneck".
I was referring to more specific bottlenecks, rather than one giant generalization. Other benchmarks have proven that PCI-Express is by far the least limiting factor of overall system performance than say, SATA. So in terms of priority in increasing performance SATA>PCI-Express. In the same way, in prioritizing the increase in performance of a consumer gaming PC with a discrete GPU the order is generally, GPU>CPU>RAM because of the simple fact that games are more GPU bound than CPU-bound, and likewise more limited by CPU frequency than RAM frequency. Discrete GPUs are not really affected by RAM speeds since they have their own large store of VRAM unlike the CPU which has very tiny caches. APUs are different since they're basically GPUs+CPUs in one, but without the large VRAM. Thus they are more reliant on faster system RAM which now has to do double-duty as the VRAM and the system RAM at the same time, so naturally higher RAM speed = higher performance, but as we've seen, only up to a certain point, after which further increases result in declining returns.
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Hypothetically, if you were to continue to increase the data rate of the system's memory you would see performance gains up until the point where the GPU's instructions units can no longer make use of the available interface."
Again, I didn't say there wouldn't be any increase. I said there wouldn't be any
significant increase, or does my understanding of "diminishing returns" differ from yours? I draw my assertions from the numbers presented in the article, not hypothetical conjecture or theoretical maximums. Did you not notice how increasing the rate from 2133 to 2400 yields a difference that's practically margin of error? Not only that, there's a "trend" of decreasing performance gains in each successive bump in frequency. Going from 1600 to 2133 is a difference of 533 and yields a significant increase. But does going from 2133 to 2400 yield precisely half the increase of going from 1600 to 2133? Nope. There is a massive drop in performance gained per increase in MHz.
The numbers don't lie.
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Having said all that, until DDR-4 is out we can't say for certain that it will not have a huge impact on both AMD and Intel systems. This is because if DDR-4 manages to lower latency or greatly increase bandwidth you will see gains, especially if DDR-4 is able to achieve both lower latency and higher bandwidth at the same time."
There is fundamentally no difference between DDR, DDR2, and DDR3. Each successive generation increases the bandwidth respective of latency, and perhaps lowers power consumption a bit. That's it. If you're expecting DDR4 to radically change this scheme, prepare to be disappointed. DDR4-2800 won't be any different from DDR3-2800.
Hypothetically speaking, if you were to snatch some DDR4-4266 memory from the future and plopped it into today's APU benchmark system with a magical BIOS update that gets everything working as it should, will you see double the performance of DDR3-2133? If real-world results mean anything, the answer is a resounding NO.
THIS is what I mean by RAM speed stops being the primary bottleneck in today's APU systems at around DDR3-2133. If DDR4 suddenly arrived tomorrow, will it make any difference with current APUs? Based on what we've seen, (wishful thinking aside) definitely not. Just like if PCI-Express 4.0 arrived tomorrow, will we see any difference with current discrete GPUs? Nope. How do we know this?
Because going from PCI-E 3.0 x8 to PCI-E 3.0 x16 yields no appreciable gain whatsoever, and that's doubling the bandwidth.
Of course APUs of the future will most likely benefit from faster DDR4 RAM. That's just stating the SUPER OBVIOUS. Just like saying "the GPUs of the future will benefit from PCI-Express 4.0".
I'm not denying the SUPER OBVIOUS.
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Oh and, to correct your first inaccuracy, DDR-4 will be lower power than what is currently available so it will use less electricity than DDR3-2400 therefore providing more performance per Watt of energy used."
I don't think you read what I said correctly. Read it again. Slowly this time. I said DDR4 won't provide any significant savings in energy consumption since RAM in general consumes negligible amounts of electricity.
What proof do I have? Just the readings of something called a "Kill-A-Watt" meter. Going from regular voltage DDR3 RAM to Low-voltage DDR3 RAM lowers the annual cost of your PC's electricity consumption by how much? Zilch. Nada. Nothing.
Even if RAM used ZERO watts, you STILL wouldn't save anything off your electric bill. It's
that negligible.
Do you understand what I'm saying now?
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