Valve's recently revealed specifications for its "Steam Machine" line of PCs designed for the living room proved to be almost the complete opposite of what we were expecting. If the prototype hardware is any indication of the firm's plans for the final product, we're not looking at a range of devices aimed at challenging the position of the next-gen consoles - for now at least. Rather, what we have here are well-specified gaming machines aimed at the PC faithful, almost certainly with premium price-tags to match.

CPU-wise, Valve hasn't skimped in its prototype line-up - for the most part. We're looking at the latest Intel "Haswell" parts, specifically the 3.2GHz quad-core i5-4570 and the 3.5GHz i7-4770. These are highly capable processors, but with a price-tag to match. Compare and contrast with AMD - its current enthusiast flagship, the FX-8350, is around £80 to £100 cheaper than the 4770K, and actually matches or even beats it on highly threaded games like Crysis 3 and Battlefield 4, where it easily beats the similarly priced i5-4570.

The arrival of next-gen consoles finally gives AMD the price vs. performance win it's been looking for in gaming, but the vast majority of the Steam library will still run better on Intel processors as games tend to be optimised for two or four cores, rather than the six or eight that greatly benefits AMD. But there are other considerations beyond raw power: the fact that Intel offers cooler processors and higher performance per watt will also have factored into Valve's decision making - Intel's sheer efficiency makes it the default choice for providing capable gaming hardware in a small form factor enclosure. However, the consequence of choosing Intel over AMD is that the machines will prove more expensive to build, resulting in higher prices to consumers.

There's also concern about the inclusion of the Core i3 CPU in Valve's proposed line-up - presumably for the entry-level Steam Machine offering. Take a look at the recommended specs for Watch Dogs - we had harboured the hope that the weak CPU cores in the next-gen consoles would help keep the PC requirements down, but in actual fact, we're seeing the exact opposite. Not even the gamer's favourite - the Core i5 quad - makes the cut for the recommended spec. Developers are finally making use of eight hardware threads - be they virtual as in the Core i7, or physical as with AMD's FX-8350. While we expect i5 quads to remain perfectly adequate (particularly as the K versions are eminently overclockable to reach stock i7 performance), we know from our continued testing with last year's dual-core Digital Foundry PC that sustaining the optimal 60fps requires serious CPU power. Next-gen just took the requirement to the next level, and our worry here is that the i3 just isn't going to cut it.

"The Steam Machines prototypes are all based on standard parts you can build yourself. It's the form factor of the unit and the innovative controller that will make it stand apart."

Aside from some nebulous concept art, we have no real idea of the form factor of the Steam Machines - aside from its 30.5 x 31.5 x 7.5cm dimensions. In terms of overall volume, that's a fair bit smaller than an Alienware X51.

Graphics, storage - and the form factor GPU-wise, we're also in familiar territory, with Nvidia chosen to supply four different graphics cards for the Steam Machines - the GTX 660, a solid start for value-conscious 1080p gaming, all the way up to the GTX 780 and GTX Titan, premium-priced graphics cards that only the most dedicated of enthusiasts can afford. Between the two extremes we have the £200 GTX 760 - pretty much the sweetspot in terms of price vs. performance in Nvidia's line-up. Curiously, Valve is suggesting that it is targeting 3GB of GDDR5 framebuffer memory for its hardware, when only the GTX 780 actually supports it. Titan ships with twice that amount while the lower end cards offer 2GB (though custom configs could bump that up to 4GB). This element of the spec does suggest that Valve does have an eye towards some of the upcoming trends in PC gaming - namely the requirement for generous amounts of video RAM brought about by the unified 8GB of memory found in both PlayStation 4 and Xbox One. The lack of any kind of AMD graphics hardware is perhaps surprising, but Nvidia has generally tended to be more supportive of the Linux platform than its competitors, something that AMD revealed it is looking to address at its recent GPU14 event. There's also the fact that on the higher performing graphics cards, once again there is a greater level of performance per watt compared to AMD counterparts, making the green corner's offerings more amenable to a small enclosure. Nvidia generally appears to have a more refined design in its Kepler architecture, while AMD has remained competitive by increasing clock-speeds - hence the Radeon HD 7970 GHz Edition, and its extremely similar successor, the Radeon R9 280X (which we're reviewing imminently). Update: Valve has now revealed that we will see Steam Machines with AMD and Intel graphics hardware. "Last week, we posted some technical specs of our first wave of Steam Machine prototypes," Valve spokesman Doug Lombardi said. "Although the graphics hardware that we've selected for the first wave of prototypes is a variety of Nvidia cards, that is not an indication that Steam Machines are Nvidia-only. In 2014, there will be Steam Machines commercially available with graphics hardware made by AMD, Nvidia, and Intel. Valve has worked closely together with all three of these companies on optimizing their hardware for SteamOS, and will continue to do so into the foreseeable future." "Windows benchmarks of Valve's chosen GPUs represents a doubling of performance between the GTX 660 and the GTX Titan. The Titan's inclusion is a little bizarre bearing in mind that the GTX 780 offers almost the same level of gaming power." 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 So what kind of performance does Valve's preferred graphics cards offer at 1080p resolution? Here we test the GTX 670, GTX 760, GTX 780 and GTX Titan at 1080p ultra settings (or equivalent) in our benchmark suite. This gives an idea of relative power - the benchmarks are from Windows versions, so there's the possibility that SteamOS/Linux performance could be very different. 1920x1080 GTX 660 GTX 760 GTX 780 GTX Titan BioShock Infinite, DX11 Ultra DDOF 52.3fps 65.9fps 94.6fps 101.1fps Tomb Raider, Ultra, FXAA 60.1fps 76.8fps 116.6fps 130.2fps Metro 2033, Very High, 4x MSAA 25.8fps 31.5fps 47.5fps 49.0fps Metro: Last Light, Very High, SSAA 21.4fps 27.0fps 40.0fps 43.0fps Hitman: Absolution, Ultra, 8x MSAA 22.8fps 31.0fps 47.0fps 49.8fps Sleeping Dogs, Extreme 37.9fps 41.1fps 58.0fps 66.5fps Elsewhere in the design of the prototype Valve machine we see another interesting inclusion - a 1TB/8GB hard drive/SSD hybrid. These have the form factor of a standard laptop drive, just like the hard disks used by the consoles, the difference being a caching mechanism that mirrors the most highly utilised sections of the HDD into solid state memory, providing significant speed gains. Generally speaking, Linux is highly frugal on space in comparison to Windows: a majority of the OS files could reside permanently in that SSD partition, producing a very fast experience. So far, so good - we're looking at standard PC parts that we have a working understanding of. Indeed, factoring out the high-end GPUs, we actually already have a Steam Machine of sorts you can go out and buy today - the Alienware X51 R2, available with many of the spec options found in the Steam prototype. The X51 did a great job in refactoring the PC into a console-style shell, but Valve's design is noticeably smaller. Dimensions of the Steam Machine prototype weigh in at 30.5 x 31.5 x 7.5cm - that stacks up favourably against the 34.5 x 32 x 9.5cm of the Alienware device, but it is worth remembering that the X51 incorporates an optical drive and supports full desktop hard drives. Valve's offering features a 450W power supply, which we suspect will be internal to the enclosure (another advantage over the X51), but aside from that, nothing is known about the design - aside from the notion that the casing's CAD designs will be open source, available to any one to duplicate, or enhance. We can be reasonably sure that the Mini-ITX form factor is utilised for the motherboard - Valve is promising that all parts of the design are upgradable, and Mini-ITX is effectively the only size that fits into the enclosure. "How can Valve cram so much high-end PC componentry into so small an enclosure? A look at Alienware's X51 offers up an object lesson on how it can be achieved." Gallery: So how can Valve cram high-end PC tech into a tiny form factor? This teardown of the Alienware X51 R2 should give you some idea. As you'll see, standard desktop parts are used - at the end you can see that the GTX 670 Alienware chose is identical to the standard Nvidia reference card. Valve opts for a laptop-style HDD and no optical drive, which should allow the Steam Machine to be even smaller. 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 The form factor could make or break the Steam Machines - it's the standout element of the spec that differentiates it from a PC you could build yourself. We're really hoping for an ambitious design here - one that firmly establishes PC as a viable living room box. The importance of the casing can't be underestimated - it defines the product. At its heart, the Alienware X51 is a fairly standard gaming PC, but it's that chassis that makes it a noteworthy piece of kit, and we're hoping for something even more impressive from Valve.

Potentially revolutionary controller The design for the controller certainly hints at something really special cooking up in the labs in terms of hardware design. Valve has been fascinated with revolutionising the interface between player and game for years, but it appears that previous hardware designed to read a player's biometrics has given way to something more practical - specifically a dual touchpad controller that vaguely resembles a standard gaming controller, but has binned off the standard DirectX pad interface in favour of a far more ambitious approach - namely the emulation of mouse and keyboard. Nothing can quite match the feedback you get from moving thumbsticks, but Valve recognises this and has come up with a solution, employing "dual linear resonant actuators" - a kind of next-gen rumble, if you will. "These small, strong, weighted electro-magnets are attached to each of the dual trackpads. They are capable of delivering a wide range of force and vibration, allowing precise control over frequency, amplitude, and direction of movement," says Valve. "This haptic capability provides a vital channel of information to the player - delivering in-game information about speed, boundaries, thresholds, textures, action confirmations, or any other events about which game designers want players to be aware. It is a higher-bandwidth haptic information channel than exists in any other consumer product that we know of. As a parlour trick they can even play audio waveforms and function as speakers." On top of that, there's a range of joypad-style buttons, a PS4-style touchpad integrated into the centre of the controller, and the dual touch-controllers themselves are clickable too. The idea behind all of this is straightforward enough - all PC games support keyboard and mouse, there's a higher degree of control fidelity, and supporting that rather than standard joypad controls opens up a whole new range of genres for living room play - RTS games foremost amongst them. Assuming the experience of using the controller works out the way Valve says it does, full mouse/keyboard emulation is a masterstroke. However, we do wonder how the feedback will work on older games (if at all) and to what extent the controller will get the bespoke integration from developers it really needs to genuinely make a difference. "Valve's intention with the Steam Machines pad is to allow for all game types to be playable in the living room - including genres like strategy games, which usually rely on keyboard and mouse." This diagram details how Valve has bounded Portal 2's keyboard/mouse control scheme to the new pad. Our only concern is that the standard WASD movement controls will be digital in nature and perhaps best not suited to an analogue controller with the precision Valve's pad promises.

Who will port to SteamOS? Of course, mainstream adoption is the major sticking point in the whole Steam Machines concept. Bespoke controller integration is one thing, but writing off Windows entirely in favour of Linux is another matter entirely. Valve's decision to supply its own OS essentially means that the majority of its vast library will be unplayable on these new machines - unless you shell out for a Windows license and set up a dual boot system. The short term fix is to use Nvidia Shield/Remote Play-style streaming from a Windows box located elsewhere in the home, but while we reckon this may work out OK (Shield performs remarkably well, all things considered), it's far from a premium experience. Our take? We believe that Valve is playing the long game. We saw recently that AMD is putting pressure on Microsoft with the upcoming release of its Mantle API, which offers console-style access to the GPU by effectively replacing DirectX 11. Valve's approach to muscling out DX11, and indeed Windows, centres around the application of the OpenGL API. Mantle offers a potentially explosive short term performance boost for AMD Graphics Core Next GPUs, but Valve's approach in seeking the adoption of OpenGL arguably has longer term benefits for both game-makers, and players. Building your game around OpenGL makes porting to Linux/SteamOS easier of course, but there are other benefits too - bringing your game to Mac, for example, another platform supported by Steam. Then there's the rise of mobile. Nvidia's Tegra 5, released next year, sees full OpenGL support coming to portable devices for the first time, and has the horsepower to best current-gen console (though whether the surrounding fabric matches up remains to be seen). Regardless, even in the here and now, OpenGL is gaining traction with indies because of its sheer portability - if that ability to more easily move games onto multiple platforms gains traction, Valve can only benefit, whether it's via SteamOS, another Linux variant or Mac. Whether we're talking OpenGL or Mantle, Microsoft, Windows and DirectX have never been under this much pressure. The de facto standard for games development is either under-performing, or simply not portable enough for multi-platform creators. It'll be fascinating to see how - if - the company responds. "Big Picture Mode is already fully functional in the existing Steam client and we expect the SteamOS version to be much the same." 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 There's no real secret about how SteamOS will look in your living room - the pad/HDTV-friendly Big Picture mode has been part and parcel of the Steam client for some time now. This video outlines Valve's vision for how its front-end works in a lounge environment.