AMD's APU technology - combining CPU and GPU in one chip - is well-known for offering up entry-level gaming power that significantly outperforms the Intel equivalents, usually at a very competitive price point. But in the last few months, the technology has upped its game. With the arrival of Xbox One and PlayStation 4, we've seen APU tech move on to the next level, defining the next generation of console gaming, while the latest PC desktop equivalent - codenamed Kaveri - promises to completely revolutionise the relationship between CPU and graphics tech in a way that simply isn't possible in a conventional computer.

This key new technology is called HSA - Heterogenous System Architecture - and it utilises the currently unique ability of the main processor and its GPU compute units to simultaneously access the same memory space, allowing for both components to work on the same tasks in tandem without having to shuttle data back and forth across constricted interfaces. It's an exciting technology, allowing apps to more easily take advantage of the very different processing strengths and weaknesses of the CPU and GPU architectures, with neither relegated to second-class citizen status.

The really impressive thing about HSA is that all of this cooperation between the two processing units is entirely invisible to the software - the API itself takes care of all the heavy lifting. Results in demos so far look promising, but really we're looking towards the longer term before we start seeing HSA make a genuine difference to everyday computing. Perhaps the biggest disappointment in reviewing Kaveri is that one of its most exciting new aspects currently has little relevance either to general computing or gaming.

However, Kaveri still has much to offer - specifically gamer-friendly enhancements such as integration of the firm's most recent GCN (Graphics Core Next) architecture, meaning support for the new Mantle API. Alongside that, there's dedicated TrueAudio processing silicon, which AMD reckons can significantly reduce the CPU burden on computationally expensive effects such as reverb. There are also refinements to the CPU architecture itself, which sees Steamroller take over from last year's Piledriver - bringing about improved performance plus better power efficiency. The A8-7600 we're testing has the ability to run at a miserly 45W and still hand in decent entry-level gaming performance, with the BIOS offering up the chance to "upgrade" to 65W, boosting CPU frequency - though GPU remains unchanged. Either way, we benched our entire system at just 90W during the taxing Metro: Last Light benchmark, which is pretty impressive stuff (and that's with the processing running at the 65W level).

Kaveri A8-7600 system specs Previously AMD has supplied motherboard and processor, but with Kaveri, a complete PC turned up at the Digital Foundry office, based on an AsRock FM2A88X-ITX+ Mini-ITX board, 250GB SSD and 16GB of 2133MHz RAM in a dual-channel configuration, all housed within the impressive cuboid Xigmatek Nebula casing. As for the APU itself, here's the lowdown on the raw specs of the processor we reviewed: Core Name: Kaveri

Kaveri Socket: FM2+

FM2+ CPU: Four Steamroller cores across two modules, 3.3GHz, 3.8GHz Max Turbo (65W mode)

Four Steamroller cores across two modules, 3.3GHz, 3.8GHz Max Turbo (65W mode) GPU: R7, GCN 1.1 technology, 384 shaders, 720MHz

R7, GCN 1.1 technology, 384 shaders, 720MHz TDP: 45W/65W (BIOS Switchable, CPU speed drops to 3.1GHz/3.3GHz Max Turbo in 45W mode)

45W/65W (BIOS Switchable, CPU speed drops to 3.1GHz/3.3GHz Max Turbo in 45W mode) Memory compatibility: DDR3 1066MHz-2133MHz

DDR3 1066MHz-2133MHz Other Features: HSA, hUMA, TrueAudio Kaveri is based on AMD's FM2+ platform, an evolution of the FM2 technology that supported last year's Trinity and Virgo cores. You can use those CPUs in FM2+, but if you're looking to upgrade to Kaveri, a standard FM2 board won't support it, which is unfortunate.

But to what extent can this system cope with gaming? Can it keep up with the latest and greatest titles? AMD has targeted 1080p gameplay at 30fps, but previous APUs have been much more comfortable in the 720p/768p arena. For all its improvements over last year's Trinity and Richland chips, by our reckoning it would take a massive leap in power to provide that kind of performance in a sustained manner. The A8-7600 is curious in that you can switch between 45W/65W TDPs, so we engage the higher power limit in order to give our games as much CPU processing power as possible. Overall, Kaveri hands in a pretty impressive showing, but as our Battlefield 4 testing at the medium quality level demonstrates, we're still some way off achieving anything like a consistent experience at full HD resolution. On the more taxing games at least 720p/768p remains the target, but there's enough horsepower on tap to push the quality settings significantly beyond what can be achieved with the same games running on Xbox 360 and PlayStation 3.

This content is hosted on an external platform, which will only display it if you accept targeting cookies. Please enable cookies to view. Manage cookie settings Kaveri, Battlefield 4 - let's do it. Here we compare 720p on medium settings with v-sync enabled to the same action running at full HD 1920x1080. AMD reckon that Kaveri is good for 1080p gaming, but we believe that the A8-7600 at least is best utilised at 720p or 768p, though dialling down quality presets significantly opens the door to higher resolutions.

It's fair to say that BF4 is a fairly challenging game from a tech perspective - especially on the South China Seas aircraft carrier setpiece - so we rolled out our existing range of benchmark titles to see how they fared with the new APU. However, judging exactly what to bench was quite challenging. After all, the 384 GCN stream processors in the A8-7600 are exactly half that of the Xbox One, while frequency is limited to 720MHz, up against the 853MHz in the new Microsoft console. We're looking at some kind of midway point between last-gen and next-gen console performance.

However, the real challenge Kaveri faces is the fact that the GPU component has no access to ultra-fast GDDR5 RAM - instead, the DDR3 RAM installed on the motherboard is utilised for graphics tasks - something for which it wasn't really designed as the raw bandwidth simply isn't there. There's been a lot of talk about AMD potentially releasing a powerhouse APU for PC based on the PS4/Xbox One designs, but in the absence of GDDR5 or a similarly fast equivalent, that really doesn't make sense - the compute units simply couldn't be fed data fast enough. That said, DDR3 comes in many flavours: the faster the RAM you have, the better Kaveri performs. For the complete system that AMD supplied, the firm took no chances, fitting enthusiast-standard 2133MHz modules in a dual-channel configuration.

In addition to running our standard benchmark suite, we also spent some time playing the games, with Tomb Raider in particular occupying much of our time. On medium settings, the game was essentially unplayable at 1080p, while 1600x900 gave console-style performance - albeit with some real fluctuations in frame-rate whenever the game utilised water effects (or any other kind of alpha) extensively. In short, even with 2133MHz RAM, you're constantly battling RAM limitations.

To give a decent idea of how well the A8-7600 works across a range of gaming conditions, we ran the same titles on the same medium settings across three resolutions: 1280x720, 1600x900 and 1920x1080. It's telling that only Sleeping Dogs showed any sign of being playable at 1080p, suggesting that lower resolutions are essential for a fluid experience on any modern game. We feel we could work with 1600x900, but perhaps unsurprisingly the APU provided the best performance on all titles tested at 720p - indeed, outside of the benchmark during actual gameplay, we could even run Tomb Raider at high settings with consistently decent frame-rates. It felt almost like a high-end PC experience, just running at Xbox 360 resolution.

"Limited GPU resources and comparatively slow RAM access limit Kaveri's potential, but wise settings selection and realistic resolution choices yields good results."

This content is hosted on an external platform, which will only display it if you accept targeting cookies. Please enable cookies to view. Manage cookie settings A rundown of the A8-7600's gaming performance across our usual suite of benchmarking titles. Here we've opted for medium quality settings, but removed expensive additional effects and kept MSAA completely out of the equation. Multi-sampling just isn't compatible with the bandwidth limitations APU technology has to work around.

1280x720 1600x900 1920x1080 BioShock Infinite, Medium 47.3fps 33.7fps 25.2fps Tomb Raider, Normal 55.1fps 38.1fps 27.8fps Metro 2033, Medium 42.2fps 32.5fps 26.0fps Metro: Last Light, Medium 34.3fps 25.8fps 19.6fps Hitman: Absolution, Medium 36.1fps 28.8fps 23.1fps Sleeping Dogs, Medium 59.6fps 45.2fps 27.2fps

So in theory, Kaveri's looking pretty decent at this point, but one thing bothered us during our testing: AMD's APUs are geared towards entry-level gaming PCs and yet the test unit is packing high-end memory that out-specs the more mainstream 1600MHz modules routinely found on the market today. Indeed, RAM prices have shot up over the last year, and often the best deals to be found involve locating older 1333MHz stock. Our worry was that this review would not be indicative of real-life performance because an entry-level processor was seeing its results augmented via enthusiast-standard RAM.

Dipping into the BIOS, we reduced frequency down to 1333MHz, 1600MHz and 1866MHz in an effort to emulate the performance of RAM modules more likely to be paired up with the new APU. Then we re-ran the 720p benchmarks to see what impact the reduced bandwidth had on gaming frame-rates.

The results are enlightening. Stepping down from 2133MHz to 1866MHz offers the smallest drop in performance - around seven per cent all told - but that figure moves into the double digits as you drop down from 1866MHz to 1600MHz, and then again from there down to 1333MHz. Comparing the slowest memory tests to the fastest, we find that 1333MHz DDR3 dual-channel frequencies offer around 78 per cent of the performance of the fully maxed out system, and a fundamentally different gameplay experience.

Also, suffice to say that you'll need to use two matching memory modules in order to utilise dual-channel operation, otherwise you're looking at an enormous drop in throughput, effectively crippling the APU. Utilising two sticks of RAM is pretty much the norm on most PCs, but during recent testing on another project we're working on, we found that using just one stick of RAM had negligible impact on gaming frame-rates on a traditional gaming rig with a dedicated graphics card. Onboard GDDR5 seems to be a far, far more important component to gaming performance on a standard gaming PC as opposed to single or dual-channel RAM, or its speed.

"Available memory bandwidth is hugely important for Kaveri, which could be a problem for a budget processor likely to be matched up with slower mainstream DDR3 modules."

This content is hosted on an external platform, which will only display it if you accept targeting cookies. Please enable cookies to view. Manage cookie settings AMD's test unit arrived with expensive 2133MHz DDR3 RAM, in effect giving the APU as much bandwidth as the platform could deliver. However, matching a budget processor with high-end RAM seems an unlikely pairing, so we reduced bandwidth on the modules in order to give some idea of how the system copes with more keenly-priced memory.

2133MHz 1866MHz 1600MHz 1333MHz BioShock Infinite, Medium 47.3fps 44.4fps 40.1fps 36.4fps Tomb Raider, Normal 55.1fps 51.5fps 48.2fps 43.7fps Metro 2033, Medium 42.2fps 39.4fps 35.2fps 31.2fps Metro: Last Light, Medium 34.4fps 32.0fps 28.3fps 26.1fps Hitman: Absolution, Medium 36.1fps 33.3fps 30.2fps 27.2fps Sleeping Dogs, Medium 59.6fps 55.3fps 51.2fps 46.9fps

Overall results during our testing weren't bad at all, bearing in mind the cost of the A8-7600 and the really tight TDP window the processor has to operate in. We gave Mantle a quick test and can confirm that it is fully armed and operational on the latest 14.1 AMD beta drivers, and it provides a small uptick in performance on Battlefield 4 - just as long as you don't engage v-sync. The game seems to disagree with it massively, crippling performance levels in comparison to the standard DirectX 11 renderer.