Intel Core i7-3960X Review
Intel Core i7-3960X
The diagram of the CPU die shows the deceptively simple layout of the various components. We're sure we can't be the only people who've noticed the 8 Core spaces only filled up by 6 Cores. The ones we do have each support a single Hyper-Thread, giving us 12 threads on this particular CPU. The cores have 32KB of instruction cache and 32KB L1 cache. Level 2 cache is provided by 256KB of shared instruction and L2 cache, whilst 15MB of L3 cache is shared between the cores, with up to 2.5MB available per core.
The Memory Controller is retained on the CPU, continuing the trend that Intel have had for a few processors now. Equally the I/O is also integrated. The merging of the Southbridge onto the CPU is expected in the next revision.
The diagram on the right shows that the new 2011 processors support Quad Channel RAM, for those of you with a unquenchable thirst for memory. It does however state the PCI Express is 2.0, whereas it's up to 40 lanes of PCI Express 3.0, as indicated in all the other literature, and the physical board itself. See the slide below for further clarification, or muddying depending on your outlook.
There are a lot of tweaks behind the scenes that to you and me, the average end-user, aren't worth going over too much. We're fairly certain that if you're the kind of person who needs to know that the i7-3960X supports "46 bits of physical address space" and has "static lane numbering reversal and polarity inversion support" then you'll be more willing to delve into the finer points of the documentation.
For us though the important things are neatly summed up in the following slides. 6 Cores hyperthreaded cores giving us 12 threads to play with is the same as all the high-end X58 processors. The really big adjustment for our fun and games is the move from the initially expensive and under-performing Triple Channel RAM of the X58 boards into the world of Quad Channel memory. Thankfully because the LGA2011 is based upon the already successful LGA1155 dual-channel RAM, it's a simple upgrade as the memory is already available at the required voltages.
This left-hand slide also indicates that the combination of the Core i7-3960X and X79 chipset enable the support for PCI Express 3.0, without stating which of the two actually provides it. Given that you can't have one without the other it's not hugely important. What matters is that it supports PCIe 3.0.
We will get into the overclocking side of things more when we take a look at the BIOS on the DX79SI motherboard, but for now it's worth noting some very cool changes. Rather than the simple but limited overclocking available on the SandyBridge, or the complex but open-ended overclocking we saw from the X58 series, the LGA2011 has a nice middle ground. The 'automatic' overclocking actually takes into account the uprated voltages and TDP limits needed to stably sustain an overclock. Also the memory isn't limited to the rather coarse dividers we saw in Sandy Bridge, but there is a 1.25 'gear' option that allows for 1666MHz or 2000MHz. Good for getting a little extra performance without crossing the yawning chasm between 1866MHz and 2133MHz.
Finally we see where Sandy Bridge E, LGA2011, fits in the Intel Roadmap. We can also see the potential performance improvements of the combination between the Core i7-3960X and the Intel DX79SI motherboard and the old X58 i7's. Testing the performance is obviously what we're here for, but before then let's grab a look at the motherboard today's fun is being held on.