Intel releases Ivy Bridge CPUs. We review the i7 3770K

Adam Oxford at

ivy bridge review

Chin up CPU fans, Intel has launched its latest batch of processors out into the world today. On this fine anniversary of Shakespeare's birthday an infinite number of monkeys has been hard at work producing a replacement for the entire Core i7 and Core i5 range - not that they needed it - and Intel have crossed over Sandy Bridge and are onto a new Ivy Bridge design.

And we've had one of these new chips in the office to play with for a couple of weeks. Want to know what we think? Read on.

Officially, Ivy Bridge is being marketed as the 'third generation Intel Core processor', and you'll be able to distinguish it from older designs by a '3' prefix to the model numbers. Like its predecessors, Nehalem and Sandy Bridge, it will come in Core i3, Core i5 and Core i7 flavours.

There's more similarities. Ivy Bridge doesn't require a new CPU socket, and will fit 1155 pin series 6 motherboards (although it will require a BIOS update). Here's a recap of the major differences between the three lines.

  • Core i7 Quad core processors with 6MB of on board cache, integrated graphics and a turbo mode for automatic overclocking if there's demand for more computing power and the chip hasn't exceeded its arbitrary power limits. These also include Hyperthreading – a technology which allows two program thread to run simultaneously on a single execution core.
  • Core i5 Almost identical to Core i7, except for the omission of Hyperthreading and a slightly smaller amount on board cache memory.
  • Core i3 Dual core versions of the same architecture, with a lesser able graphics processor and no Turbo mode. They do have Hyperthreading, though, so your PC sees them as having four cores.

These descriptions only apply to desktop chips. There are different designs for laptops which include dual core Core i7s and other unusual arrangements. Make sure you check the specs carefully on a portable before you buy. Any model with a 'K' suffix has an unlocked clockspeed multiplier, which means its easy to manually overclock without messing around with your motherboard's basic timer.

We've had the unlocked Core i7 3770K to play around with, which is the highest specced and most expensive of the new CPUs. By underclocking in and disabling Hyperthreading, it's easy to get an idea of how most of the range will perform.

The basic design of Ivy Bridge isn't significantly different to previous processors. There are a few tweaks to the architecture to support faster RAM, PCI Express 3.0 and faster encryption, but the major change is to the graphics core. The new HD Graphics 4000 supports DirectX 11 and increases the number of unified shaders to 16 – not enough for Battlefield 3, although it is more capable of gaming if you're after an Ultrabook. More on the performance benchmarks in a moment.

Ivy Bridge is more interesting because it's the first chip produced on Intel's 22nm technology, down from 32nm for Sandy Bridge. That means faster clockspeeds and lower power consumption. Even better, due to the physical restrictions of making semiconductor gates at these improbably small scales it uses the excitingly named '3D tri-gate transistors' which Intel is pioneering here. These basically involve extruding gates upward rather than down flat to increase the surface area available to electrons for activation, rather than laying them down flat.

That's quite an achievement to get into mass production, but should you upgrade to Ivy Bridge?

I won't bore you with too many benchmarks here – there are plenty of other sites for that - but the upshot is that Ivy Bridge is consistently faster than Sandy Bridge in every test I've run. Plus, getting the Core i7 3770K to run stably at 4.5GHz was the effort of a single mouse gesture, swiping the clockspeed slider in the new Z77 BIOS. The new BIOS doesn't even mention the base clockspeed, either – it sensibly just gives a target for the turbo mode to try and hit.

If you've already got a Sandy Bridge quad core, though, you can put your money away. Ivy Bridge has the edge in theoretical tests and is quicker for CPU bound tasks – but not enough to warrant replacing your current chip. With anything that's Core i5 or above, games performance is much more likely to be held back by your graphics card than your CPU – if something's unplayable now, then it's unlikely that a new processor is going to give you a meaningful boost. Look at the Heaven 2.5 score below - once you start running games at normal resolutions, they're almost entirely GPU dependent. The gaming benefits of upgrading from an older Core 2 Quad will be more to do with low power and less noise, too.

If you're upgrading anyway, however, there's no reason to buy anything other than Ivy Bridge. Intel has kept the pricing down to the same levels as the last generation, and will presumably be phasing out older chips before they can be offered at a discount (which is what happened when Sandy Bridge took over from Nehalem).

That said, it'll be more likely you'll want the Core i5 3570K than this. We haven't had one in the office yet, but simulating the clockspeeds and number of cores (essentially turning off Hyperthreading) on a Core i7 3770K still outperforms the older Core i7 2770K, which yesterday cost about £100 more than a top end Core i5.

There's only one slight disappointment, and that's that swapping an Ivy Bridge chip for a Sandy Bridge chip didn't alter power consumption significantly on the test rig (a Z77-based PC with an AMD HD7850 graphics card). Rather, the extra thermal headroom has been turned into a performance gain across the board.

What of the new graphics core? It's about twice as fast as the old one in Far Cry 2, but only about 10% faster in SW:TOR. It's easier to get games running without a discrete card – which is good news for laptops – but still not really up to much.