Memory Architecture: Does Losing One Channel Hurt?
You “lose” two things in stepping down from an LGA 1366-based interface to the LGA 1156 Core i7 (three things if you go for a Core i5). There’s the triple-channel memory architecture, enough PCI Express 2.0 via X58 to give each graphics card in a CrossFire or SLI config its own x16 link, and, in the case of i5, you also lose Hyper-Threading.
We already know that Hyper-Threading can be a big boon if you’re running the right apps. We know that the PCI Express situation really isn’t that big of a deal. But what about the memory subsystem? Technically, Lynnfield’s two channels of DDR3-1333 come within 4 GB/s of Bloomfield’s three DDR3-1066-capable channels. But those specs mean very little to the power users willing to shoot for 1,600, 1,866, or 2,000 MT/s.
Because we’ve found very little reason to recommend anything faster than DDR3-1333 (at least as far as performance goes), we’re arming our X58 platform with two and three channels of DDR3-1333 memory and our P55 test bench with two channels of the same stuff running 7-7-7-20-1T timings.
There’s clearly a massive throughput advantage with three channels of DDR3 memory. But as we’ve seen over and over, it doesn’t necessarily translate over into the real world. If you were worried about a negative impact on performance due to Lynnfield’s memory controller, don’t.