For a long time, both Intel and AMD relied on ever increasing clockspeeds for each new processor release. That still remains the case today, but to a much lesser degree. Case in point - Intel's long retired Northwood line topped out at 3.4GHz, or 200MHz faster than the zippiest Core i7 processor currently on the market.
The future of chip design has shifted to where multiple cores is now main factor, supported by larger cache, on die memory controllers, expanded instruction sets, and other secondary concerns. That's all well and good that AMD and Intel are on the same page, which puts the onus on software developers to catch up, but at least one group of researchers believes we're headed for an unpleasant surprise.
According to Sandia National Laboratories, performance is going to start tapering off significantly as chip makers keep piling on more cores. Sandia came to the conclusion by running a simulation consisting of "key algorithms for deriving knowledge from large data sets." During the simulation, few performance gains were had from moving from four to eight cores. But the real kicker is going beyond eight cores resulted in a performance drop. When that number gets as high as 16 cores, Sandia warns "a steep decline is registered as more cores are added."
So what the heck is going on that would cause multiple cores to stumble so unexpectedly? It comes down to a bottleneck in memory bandwidth. And what's scary is that the bottleneck isn't an unknown problem, but "it isn't an issue to which the industry has a known solution, and the problem is often ignored."
We're still quite a ways off from 16-core processors making it into the mainstream, and developers have yet to fully tap into even dual-core processors on a consistent basis. So while there's plenty of time to come up with a solution, chip makers haven't yet started doing so, according to Sandia.