Buying Guide: From £85 to £260 - find the best processor for you
Every year, CPUs get faster. That's how PC technology rolls. But once in a while, a new processor comes along that slaps the market upside the head and forces a change in expectations in terms of value and performance. Intel's new Sandy Bridge chips do just that.They're game changers for both good and bad. For starters they're bonkers quick. The new quad-core Core i7 2600K is so fast, it makes Intel's six-core Core i7s look overpriced and silly.
Sandy Bridge also brings several new technologies to the table including a pukka fusion architecture - that's CPU and graphics processing on the same slice of silicon - and heterogeneous computing. If that sounds like digital double-speak it essentially means the new Sandy Bridge chips have specialised circuitry designed to do specific jobs, such as video encoding, faster than ever before.
Of course, Intel's Sandy Bridge processors don't make every other CPU on sale instantly redundant. But they do demand a reassessment of what represents both value for money and a sensible upgrade path.
If, for instance, you are currently running an older Intel Core 2 processor, does it make sense to build a new system based on the Intel LGA1,156 socket bearing in mind that Sandy Bridge chips require the latest LGA1,155 socket?
Likewise, while many AMD CPUs certainly offer superb value for money, the performance gap to Intel has now grown to truly epic proportions. Chips towards the top of AMD's price list certainly look precariously positioned.
Then there's the question of overclocking. It's disappointing that Intel has decided to severely limit overclocking with most Sandy Bridge chips. Even so, the unlocked K series are absolute screamers.
You could also argue Intel's latest chips are so powerful, overclocking is unnecessary.
The other major question Sandy Bridge poses is whether you need a discrete graphics card. For sure, if you're remotely serious about gaming, a pukka graphics card is essential. But for everyone else Intel's latest integrated video core is good enough for light gaming and has a superb 2D feature set. Time to reveal our thoughts…
If you're boning up for any kind of CPU upgrade or overhaul, you need to know about Intel's new Sandy Bridge chips. That's not because they're the only sensible choice. It's a question of context. You simply cannot judge the merits of other CPUs or appreciate the direction of PC technology development unless you understand what makes Sandy Bridge chips tick.
First, you'll need to identify the new Sandy Bridge processors in Intel's stupidly overcomplicated price lists. In its infinite wisdom, Intel has carried over the Core i3, Core i5 and Core i7 branding. Similarly, Intel has maintained the essential meaninglessness of those labels.
Yes, performance and features tend to improve as the number increases. But just like existing i3, i5 and i7 chips, there's no consistency. A Sandy Bridge Core i5 might have two cores. But it might also have four. Dumb.
Anyhow, the way you identify the new Sandy Bridge processors is the quadruple-digit '2000' suffix. Thus, the Core i5 2500 is a quad-core chip supporting four threads and an official clockspeed of 3.3GHz, while a Core i7 2600 is a quad-core chip with eight threads and a 3.4GHz clock. Got that?
At launch, there are 13 Sandy Bridge processors ranging from dual-core, quad-thread chips through to quad-core, eight-thread models. As if that wasn't baffling enough, some of those 13 launch CPUs are further distinguished by a suffix letter.
T and S series processors are low power variants. For instance, the Core i5 2500T is rated at just 45W compared to the 95W of the standard i5 2500.
Finally, there are the K series chips. Currently, there are just two, the i5 2500K and i7 2600K. They're identical to their letterless brethren save for one crucial feature, an unlocked CPU mulitplier.
As we'll see, thanks to Intel's new attitude to overclocking that's an extremely important distinction.
Subtle details
In terms of basic architecture, the CPU side of Sandy Bridge doesn't look that special at first glance. Intel is sticking with dual and quad-core models at launch with six and eight-core versions to follow.
Intel hasn't revealed launch dates for these more powerful chips, but we're expecting the six-core model in the second half of 2011 and the eight-core monster in 2012.
All Sandy Bridge processors are sired by Intel's most advanced 32nm production process, which is around half way through its two-year shelf life. Internally, Intel has overhauled Sandy Bridge's execution cores, netting roughly 10 per cent more performance per core and per clock cycle.
If that doesn't sound dramatic, Intel has seriously cranked up the clocks. That's not immediately obvious from the headline specifications. The top 2600K chip, for instance, is officially a 3.4GHz. That's only slightly quicker than Intel's performance king, the 3.33GHz Core i7 980X.
But here's the thing. The 2600K slots in at the high end of Intel's mid range. It costs about the same as the existing Core i7 875K, a 3.06GHz processor. That's not all. With Sandy Bridge, Intel has introduced the 2.0 revision of its Turbo Boost technology.
You can read our detailed thoughts on Turbo Boost 2.0, both good and bad, in the 2600K review. But for now, simply know this. In our experience, the 2600K runs at 3.8GHz regardless of how many cores are active. It's one quick puppy.
Raw CPU power alone would be enough to recommend the new Sandy Bridge family. And yet these chips have some seriously special sauce that has nothing to do with traditional PC processing.
Instead, Sandy Bridge breaks new ground in graphics. Firstly, it's the first bona fide fusion processor. That means it has both CPU cores and graphics processing on a single slice of silicon. It's all part of a broader trend towards system-on-a-chip (SoC) in all digital devices.
Smartphones are rapidly closing in on full SoC status and PCs won't be too far behind. Admittedly, it'll be a few years yet before the graphics core integrated into a CPU is good enough for proper gaming. But with Sandy Bridge, Intel has really lifted the game for integrated graphics.
The new HD Graphics 3000 core in the i5 2500K and i6 2600K is at least twice as fast as any previous integrated GPU. That's the good news. The bad news is that the HD Graphics 3000 and its 12 execution units is limited to those two models.
All other desktop Sandy Bridge processors make do with the HD Graphics 2000 and six execution units. What makes that really bizarre is that the other six execution units are indeed present in the other Sandy Bridge models. Intel, in its wisdom, has simply turned them off for marketing reasons.
Given that the 2500K ans 2600K are enthusiast-class chips with unlocked multipliers and therefore likely to be paired with discrete graphics cards, it's a crazy decision. If any Sandy Bridge processors really need higher performing integrated graphics, it's the lower end models that will end up in those set-top boxes and super-quiet media centres that could benefit from a boost in gaming performance.
Whatever, there's one further aspect to Sandy Bridge's near-SoC architecture and it involves another buzz term, heterogeneous computing. The idea here is that computer chips will increasingly combine both general purpose processors and purpose-built units capable of crunching particular workloads super fast thanks to hardware acceleration.
In other words, the future of PC processors is not more and more cores. In fact, it might well turn out to be the case that four traditional processor cores are enough for any future consumer-level computing task. But, courtesy of ever increasing transistor counts, those cores will be joined by a number a special-purpose units designed to tear through tasks like video encoding, encryption and, further out, perhaps even facial recognition. The specifics are hard to predict, but with Sandy Bridge, that process has started.
The relevant feature is the Quick Sync Video transcoder engine. Built into the integrated graphics core, Quick Sync Video combines dedicated circuitry with the parallel processing capability of the 3D execution units to deliver massive video transcoding performance.
Compared to even the immense software encoding capability of the Core i7 2600K, Quick Sync Video is at least three to four times quicker in comparable video encoding benchmarks. Then factor in the 2-4x performance advantage of the best Sandy Bridge chip compared to the likes of an old Core 2 Duo CPU and you have a double-digit factor performance improvement for video encoding alone.
Impressive as that is, Intel has made using Quick Sync Video thoroughly problematical thanks to limitations involving chipsets and discrete graphics. You can read more about those issues in the Core i5 2500K and and Core i7 2600K reviews. But the gist is that the people most likely to want to use Quick Sync Video are also the most likely to run into problems due to how Intel and the motherboard manufacturers have implemented the new features. It's pretty dumb.
The final part of the Sandy Bridge puzzle is overclocking. You could say Intel has spoilt us in recent years. After all, we've become accustom to 1GHz-plus overclocks on the majority of Intel chips. Just hop into the BIOS, give the baseclock a bump and say hello to 4GHz computing.
With Sandy Bridge, however, the party is over. The K Series chips aside, overclocking is limited to a maximum of 400MHz additional clockspeed using the partially unlocked CPU multiplier.
Admittedly, the K series chips are unlocked up to a theoretical 5.7GHz. But they're slightly more expensive chips - costing between £20 and £40 more than the standard model. The beauty of the old regime was that you could pick up a low-clocked cheapo version and crank it up to beyond-Extreme-Edition clocks. Those simple days are now over.
Down the upgrade path
If that's everything you need to know about Sandy Bridge, how does it plug into the CPU-upgrade conundrum?
Much depends on both the socket and CPU you are running. Starting with Intel platforms, the first thing you can do is disregard the LGA1,366 socket completely. In our esteemed opinion, it's a dead platform.
For starters, the only LGA1,366 chips that are faster than the best Sandy Bridge CPUs are the offensively overpriced Gulftown Core i7 900 series six-core models. Making matters worse, LGA1,366 is not long for this world.
When Intel brings out more powerful Sandy Bridge derived chips later this year with added cores, they'll come with yet another new socket, known as LGA2,011. Essentially, there is no upgrade path from a Gulftown processor.
Another easy Intel platform to deal with is any kind of quad-core processor in the LGA 775 socket. If your current rig fits that description, don't bother with a simple CPU upgrade. Either live with what you have for a while longer or go all the way with a Sandy Bridge based solution.
On the other hand, if you're running a low-clocked dual-core chip on LGA 775, you have more options. You could pick up a cheap quad-core Yorkfield CPU, such as the Core 2 Quad Q8300 and clock the twangers off it. We'd certainly recommend that option if it's gaming that really gets you going.
Alternatively, if video encoding is your bag, you might like to go for an AMD system based on one of the Phenom II X6 Thuban six-core processors. These can be had for less than £150. Factor in the typically low cost of AMD motherboards plus a little overclocking and you have a fairly funky encoding rig for a surprisingly low outlay.
As for owners of LGA1,156 systems, it's you we feel most sorry for. Intel has seriously shifted the boundaries in terms of price and performance with Sandy Bridge and we reckon it's shocking that LGA1,156 owners have been left behind.
To make it absolutely clear, we believe Intel could have architected Sandy Bridge to be largely or entirely compatible with existing LGA1,156 motherboards with few if any architectural compromises. Whatever the truth, the fact is there's nowhere to go for LGA1,156 users.
With AMD not currently offering anything to beat LGA1,156 systems, it's an all or nothing upgrade to LGA1,155. Sickening stuff given that LGA1,156 has been around for barely 18 months.
But what AMD systems? Traditionally, AMD pays a lot more attention to both the long term interests of its customers and backwards compatibility. Socket AM2 dates back to 2006 and yet all of AMD's current chips are theoretically compatible with AM2 boards and ye olde DDR2 memory.
In practice, your mileage will vary according to BIOS support. But there are plenty of old AM2 boards, for instance, that support the latest six-core Phenom II X6 chips. Therefore, if you have an AM2 or indeed an AM2+ board and a processor dating back to that era, it's extremely likely the most cost effective upgrade path will be an new chip from AMD. Hell, even if your budget is super-tight, you have options.
The Athlon II X4 645 quad-core is great for multi-threaded software if not so stellar for gaming. It's yours for under £90. A bargain in other words.
For AM3 owners, things are a little more complicated. If you already have a quad-core processor and gaming glory is your thing, a six-core Phenom II X6 isn't going to do much for you. In that case, you have two choices. Either you go turncoat and switch to Intel Sandy Bridge or you ride out the clock until the second half of 2011 and await the arrival of Bulldozer.
We won't know for sure until it's release, but it's currently looking like AMD's mythical Bulldozer architecture won't be compatible with the AM3 socket. Assuming your current system performance isn't getting you down, we'd be very tempted to at least wait and see whether Bulldozer delivers on the promise of a radical new CPU architecture before upgrading.
All of which means a few universal conclusions can be drawn. Firstly, both of Intel's LGA1,156 and LGA1,366 platforms should be avoided in terms of buying both a CPU and motherboard. Only LGA1,155 makes sense from Intel.
At the same time, AMD remains surprisingly relevant mainly thanks to the provision of lengthy backwards compatibility. It's a lesson Intel would be well advised to learn. That might just happen if AMD's upcoming Bulldozer chips really take the fight to Intel. Only then will Intel be forced to treat its customers right.
AMD Athlon II X4 645 - £88
Are four CPU cores as many as you're ever likely to need? Looking at Intel's monstrous new Sandy Bridge chips, the Core i5 2500K and Core i7 2600K, it's tempting to conclude just that.
For starters, they deliver enough performance to make even Intel's quickest six-core processors seem surplus to any sane requirements.
What's more, the new Sandy Bridgers introduce a new concept in personal computing that we reckon is likely to be very important going forward.
Read TechRadar's AMD Athlon II X4 645 review
AMD Phenom II X4 975 BE - £150
Another day, another minor variation on a familiar theme from AMD. By now you'll know our equally familiar refrain regarding the circa-2003 origins of AMD's performance PC processors, up to and including the latest Thuban sixcore models.
But if AMD's underlying CPU architecture is ancient, even the latest derivatives are getting on a bit.
The Phenom II X4 975 Black Edition is the newest chip in AMD's quad-core Phenom II range, but it uses the same old 45nm Deneb die first seen nearly two years ago.
Read TechRadar's AMD Phenom II X4 975 BE review
AMD Phenom II X6 1100T BE - £214
How grim are things looking for AMD right now? We refer you to the pricing of this processor. The Phenom II X6 1100T Black Edition is AMD's finest - a six-core masterpiece with operating frequencies close to 4GHz.
In isolation, it's a wonderful achievement. And yet it's yours for a little over £200. Not only is that less than a third the price of Intel's most expensive chip, the mighty Core i7 980X Extreme Edition, it's also around the same price as (or cheaper than) 13 Intel processors.
Read TechRadar's AMD Phenom II X6 1100T BE review
Intel Core 2 Quad Q9550 - £260
An Intel LGA775 processor in a PC Format group test? At the beginning of 2011? Given the shoeing we've subjected AMD to for selling ancient CPUs, you might wonder what devilry convinced us to slip in a dusty old Core 2 chip from Intel.
There is, however, some method to our madness. With this LGA775 chip, we hope to achieve two things. Firstly, we want to provide some context to the CPU market as a whole. In other words, how far have we come in the last three or four years?
Read TechRadar's Intel Core 2 Quad Q9550 review
Intel Core i5 760 - £150
Tempora mutantur, et nos mutamur in illis. So said Sir Humphrey Appleby to the hapless Jim Hacker in the old BBC favourite, Yes, Prime Minister. What Sir Humphrey meant was that times change and we must change with them.
The Intel Core i5 760 may have only been around since September 2010, but Sir Humphrey's maxim applies all the same. The problem is the arrival of Intel's new Sandy Bridge processors, and the LGA1155 socket that comes with them.
It means you can't buy a Core i5 760 with an LGA1,156 motherboard today and upgrade to a Sandy Bridge processor tomorrow. The loss of one pin with the new socket is enough to completely bork compatibility with Intel LGA1156 CPUs.
Read TechRadar's Intel Core i5 760 review
Intel Core i5 2500K - £184
This cut-price version of an all-conquering chip is very much our bag when it comes to affordable performance. Admittedly, Intel's new Sandy Bridge processors aren't strictly speaking high-end CPUs.
Intel's two six-core Westmere processors, the Core i7 970 and Core i7 980X Extreme Edition, remain top of the pile for now. But even with just four cores, the new Core i7 2600K is an absolute screamer. It's fast enough to make those six-core Gulftowns seem pointless.
What the 2600K isn't is cheap. We'd expected it to appear on our favourite online stores within dashing distance of £200. Instead, it's over £250, which only makes the new Core i5 2500K even more attractive.
Read TechRadar's Intel Core i5 2500K review
Intel Core i7 930 - £220
There can be no argument that Intel makes the fastest, most powerful and most technologically advanced PC processors in Christendom. But the chip colossus doesn't half do its best to wind us up in the process.
The Core i7 930 is a great example. It's getting on a bit, based as it is on the Bloomfield core that's been knocking around since November 2008. But it still has some impressive number crunching chops thanks to a solid specification.
It's a 45nm quad-core chip supporting eight threads thanks to HyperThreading technology, and clocks in nominally at 2.8GHz with a maximum Turbo frequency of 3.06GHz.
Read TechRadar's Intel Core i7 930 review
Intel Core i7 2600K - £251
Here's a handy fact: the future of all computing is SoC. By that we mean system on a chip, where a single slice of silicon contains everything from CPU cores to graphics, I/O, radios and more.
Already, mobile and embedded computing devices have pretty much moved to an SoC model. The PC is also on its way. That's the context you need to grasp to understand Intel's new Sandy Bridge processors in general, and the Core i7 2600K in particular.
Yes, it doesn't make sense superficially to have a high-performance PC processor with compulsory integrated graphics, but the PC will take many years to achieve full SoC status. Sandy Bridge is just one step on that path, albeit a very significant one.
Read TechRadar's Intel Core i7 2600K review
Bench analysis: Making sense of an awful lot of numbers
The benchmark figures only go on to justify the Core i5 2500K as the winner in this processor showdown. In terms of price/performance metrics, there really is no comparison.
It's startlingly close to the numbers the performance power-house i7 2600K pumps out, but is significantly cheaper. It's also made a habit in this test of out-performing the Bloomfield Core i7 930, and that's without the i7 stalwart of HyperThreading.
The i7 930 has access to eight threads of processing power compared to the Core i5 2500K's single-threaded four cores. Interestingly it's also one of the most power efficient processors in the test too, with a peak power performance bettered only by the previous generation's i5 and the Athlon II X4 645.
That Athlon II quad core chip though acquits itself well, and represents a quality upgrade for anyone still labouring under a low-end, dual-core CPU and can't afford to make the step up to a full-fledged hexcore Phenom II X6.
And the best CPU is...
Predictably enough the winner is Intel's second generation Core processors, those Sandy Bridge chips. Not only do they blow everything vaguely close to them out of the water performance-wise, but they also represent the future of processor design.
And we're not just talking Intel CPU design either; AMD is also going down the CPU/GPU fusion route represented by these system-on-a-chip (SoC) processors and cunningly calling its setup Fusion; smart cookies AMD.
We'll have the first of its Fusion chips for your delectation next month, for now though Sandy Bridge remains the finest example of graphics on chip.
The top CPU in the test though isn't the fastest of the new Sandy Bridge chips. Granted the i7 2600K is a phenomenal processor, but its relatively high price puts it in second place to its little brother.
The Core i5 2500K really is the gamer's choice right now, if you're looking to pick up a brand new gaming rig then you would do well to go for one based around this new chip.
The problem with the Sandy Bridge chips though is that what they also represent is a total rig upgrade. There's no upgrade path leading through the forest of tech to the sunlit glade of Sandy Bridge computing. Thanks to Intel's choice of a brand new LGA 1155 socket for these new chips it's a question of throwing out your existing setup and starting again from the beginning.
The fact there is only a one-pin difference between the previous Lynnfield LGA 1,156 and the new Sandy Bridge LGA 1,155 sockets feels a bit like a slap in the face to anyone sitting on a previous generation rig. Indeed those on a Bloomfield LGA 1,366 socket are likewise in the mire too.
There's nowhere to go for them either unless they want to drop £600 to £700 on a Gulftown, six-core CPU. In any case the i7 2600K is horrifically close in performance metrics to those hex-core monsters too.
This is where AMD has been the little guy's hero for the last few years. It has stuck by its sockets, offering backwards compatibility long after Intel sockets have become clogged with dust. Anyone with a DDR3-capable AMD motherboard has access to the full lineup of its CPUs, from dual-core Athlon IIs right up to the pinnacle of AMD's processor design, the hex-core Thubanbased Phenom IIs.
Whatever your budget on an AMD system then there is a CPU upgrade to match. The Athlon II X4 645 on test here demonstrates that even those with a low-end dual-core can find a quality upgrade for less than a ton. The quad-core goodness of the X4 645 gives impressive performance figures, even if its gaming power leaves a little to be desired.
At the top end of the AMD lineup though the Phenom II X6 1100T is tough to recommend. A step down the hex-core ladder though and you can pick up a number-crunching beast of a processor in the Phenom II X6 1055T for a paltry £145.
Again its gaming performance is nothing to write home about compared to the Intel CPUs, but it's pure processor performance is right up there with the best of them. Unfortunately the upgrade train is going to stop soon with the release of the AM3+ socket for Bulldozer. All existing AM3 CPUs will fit in the socket, but again thanks to a single-pin difference, the Bulldozer CPUs simply wont work in AM3 boards.
Right now though, it's all about Sandy Bridge and the Core i5 2500K in particular. If you're after a brand new rig then that's the base you want to be starting with.
We've sourced a machine from YOYOTech in the shape of the Warbird SB4.6CS, and a lovely thing it is too. But for the ultimate gaming PC you'll want to build it yourself. That way you can tailor it perfectly to your own personal needs.
