Intel Sandy Bridge Core i5 2400, 2500K, and i7 2600K Overview
Intel’s Sandy Bridge processors and new Socket 1155 have been the least-best-kept secrets of late. Following Intel’s “tick-tock” development strategy, the new chips maybe move more evolutionary than revolutionary. Still, they do bring some significant changes to the mix that promise new ways of thinking. In this article we are going to examine about Intel Sandy Bridge Core i5 2400, 2500K, and i7 2600K.
Socket 1156 isn’t that old, and now a new 1155 socket is upon us, complete with new CPUs, chipsets, and motherboards. These motherboards also bring some new and innovative features. I promise Sandy Bridge brings a slew of spinoffs and implications, and Intel has also changed the rules of overclocking.
These new Sandy Bridge chips are monsters, make no mistake. And 1155 is not a step backward from 1156; it’s quite a leap ahead in terms of performance. I’ve got locked and unlocked chips, Core i5 and i7, on the bench today: 2400, 2500K, and 2600K. These chips run the gamut of the performance lineup. Oh, and about that overclocking, be sure to carefully read that section. I think some people are in for a sobering realization of what is and isn’t possible from now on. Sub-zero cooling is about to go the way of the dinosaur.
Welcome Sandy Bridge
Intel’s development follows its “tick-tock” strategy; one swing represents a new architecture, and the next focus on process improvements. This development cycle is about 2 years each, so here we are in 2011 with the new architecture: Sandy Bridge. It’s the least-best-kept secret around, and it’s now arrived.
With Sandy Bridge comes a new socket, 1155, and it’s important to note it is not a downgrade from the 1156 socket, as you’ll soon see in our testing. This new 32nm architecture also brings a new P67 chipset for performance products and H67 chips for integrated graphics. I’ll review the chipsets in greater detail in subsequent reviews, so I’ll briefly touch on P67 today and focus on the processors themselves.
There’s plenty of more bandwidth here this time, with many PCI-E 2.0 lanes, SATA 6G, and USB 3.0. Board manufacturers will no longer need to work funky magic to make things happen.
As to the architecture itself, Sandy Bridge is an evolution of what was started in Bloomfield with an integrated memory controller. It continued with Lynnfield in the form of a PCI Express bus controller, then Clarkdale brought an integrated graphics core. Sandy Bridge takes these to a new level of refinement by bringing them all under one roof now onto one chip. CPU cores, integrated memory controller, PCI Express bus controller, and finally graphics cores are now together. One ring to rule them all, as it were.
Sandy Bridge CPUs have a 32nm process, producing smaller areas and lower voltages and temperatures as I’ve traditionally seen. There is support for Hyper-Threading, but only in certain models, along with up to 8MB of L3 cache. The memory controller remains in dual channel, same as socket 1156, with 16 PCI-E 2.0 lanes.
There’s also support for new AVX (Advanced Vector Extensions) instructions, an improvement from the previous SSE ones (256-bit versus 128-bit), resulting in greater data processing power while utilizing less computing resources. As a result, Sandy Bridge will give far better clock-for-clock performance over previous generation chips.
So this brings us to the implementation of Sandy Bridge in the form of various CPU models. There are various models but only a few major differences that set them apart in different combinations: those that are multithreaded (or not), and those that are unlocked (or not). Below is a chart that shows the differences of the Sandy Bridge processors for easy comparison. I’ll be testing each major model in this review.
A few things are immediately noticeable in the chart above. First, 2400 does not come in an unlocked version (K suffix notation), while the 2500 and 2600 do. Second, if you want a multithreaded chip, you must go with 2600 (locked or unlocked K version). Lastly, the pricing is fairly similar amongst the non-threaded 2400, 2500, and 2500K models for the most part.
The price takes a considerable jump, however, for multithreading, though the price difference between the locked and unlocked models are very modest. Our advice? For the minimal extra price, go with an unlocked K chip, the 2500K if you’re on a modest budget or the 2600K if you want a behemoth CPU. As you’ll soon see in our Overclocking section, having an unlocked chip does make a difference because the overclocking rules have changed considerably from previous generation chips.
- Core Clock: 3.4GHz, 3.3GHz, 3.1GHz
- Cores / Threads: 4 / 8, 4 / 4
- L3 Cache: 8MB, 6MB
- Max Turbo: 3.8GHz, 3.7GHz, 3.4GHz
- Max Overclock Multiplier: 57x, 57x, 38x
Each of the processors will downclock and undervolt when idle, but I’ve shown the stock speeds of each chip below. There are a couple significant changes for Sandy Bridge, as you’ll see below, which are the combination of lower bus and higher multipliers than previous generation chips. The Bus Speed (BCLK) is set to 100 while the multipliers vary, thereby distinguishing the different clock speeds of each model.
The last thing to note is that the current chips come in two steppings: D1 and D2. Stepping D1 is preferred because it will allow for higher multipliers. Eventually, all chips should reach D1 stepping, similar to the C0 vs D0 for 900 series Core i7 chips, but in the initial stages you may get a D2 chip. Enthusiasts are encouraged to search for a D1 chip or request a retailer verify the Stepping before purchase if possible.
First up, I juiced up 2400. As a locked model, I didn’t expect much overclocking, especially since our model has a D2 Stepping. I strapped on a Prolimatech Megahalems Rev. B CPU cooler, along with a Scythe Kaze 3000 high output fan and see what I could accomplish.
Finishing with a 3.91GHz result is a modest increase, nothing earth-shattering or unexpected given the locked multi. I’m still working on an early BIOS but our ASUS P8P67 Deluxe has an amazing Auto OC utility, and a BLCK of 103.0 could likely be improved if I spent more time tweaking things. On a side note, disregard the voltage shown because of the C1E, EIST, and Speedstep that must be enabled, the voltage varies according to the load, and the moment I captured this screenshot was after the voltage had dropped but the clocks hadn’t yet.
Next up I dropped in the unlocked 2500K chip, which unfortunately also had a D2 Stepping.
I managed a 4.43GHz overclock at a 43 multiplier, which is respectable. Again, for a D2 Stepping, our chip falls into the vast majority of the mid-range achievements possible with an unlocked CPU.
Lastly, I dropped in the multithreaded and unlocked 2600K, and this time I were fortunate to have a chip with D1 Stepping.
As expected, I achieved a much higher multi, finishing with a fully stable 4.84GHz overclock. I can say unequivocally that this chip can hit the magical 5.0GHz barrier on air, but I still had a bit of work to do to get it fully stable for benching. I can confirm our chip is binned though, so it’s not like any chip can hit 5GHz, as I explained on the previous page. Again, a binned D1 chip can hit 5.0GHz but it’s the luck of the draw. So anyone claiming 5Ghz is “easy” on air cooling is blowing a lot of hot air; those are golden chips.
Nonetheless, over 4.8 GHz on air without maxing out the voltage or multi is impressive. And as you’ll see next in the benchmark results, a multithreaded 2600K at 4.8GHz is an absolute monster of a chip for less than $320.
Let’s take a look at our test setups and get onto the benchmark results.
3DMark06 is a very popular synthetic benchmark primarily used for graphics card testing, but it does have a CPU component result, so I’ll focus on those scores.
The new architecture chips make a jump on the chart here. Even the quad-core 2500K can beat the hex-core AMD flagship chip. And perhaps most impressive is the non-threaded budget 2400 chip, which can match the multi-threaded i7 930.
You can also go through our this article which is on Intel Core i5 655K Processor.