While at the end of 2011 AMD gave us a rather pointless renaming of the Radeon HD 6000M family, turning them into Radeon HD 7000Ms, the new models in the family are actually arriving only now: the mobile roll out of the Southern Islands family, based on the Graphics Core Next (GCN) architecture and engraved at 28nm.
To recap, AMD has up until now developed three GCN GPUs: Tahiti (Radeon HD 7900), Pitcairn (Radeon HD 7800) and Cape Verde (Radeon HD 7700). As the first is too big to be used as a mobile GPU, the last two make up the new high and mid-range of the Radeon HD 7000M family:
Thus Pitcairn is used in the Radeon HD 7970M with a full version of the GPU which however is clocked down on the equivalent desktop version, the Radeon HD 7870 (850 MHz vs 1 GHz). This allows it to give a level of performance very close to that of the desktop Radeon HD 7850 and outdistance all the other competitor mobile solutions. AMD for example is claiming a 60% performance improvement in Battlefield 3 over the GeForce GTX 675M (renamed GeForce GTX 580M), which is currently NVIDIA’s highest performance solution, though this will no longer be the case after the arrival of the GK106 GPU this summer. With a TDP of 100W, the Radeon HD 7970M will of course be reserved for the so-called "transportable” laptops.
There will probably soon be a Radeon HD 7950M but we haven’t yet found any trace of it in the documentation from AMD, who appear to be keeping their cards close to their chest with respect to any specs.
Although its absence does create quite a hole, the other solutions on offer are likely to be the those most in demand, with energy consumption levels more in step with a maximum of laptops. The Radeon HD 7800Ms and 7700Ms are thus all based on the Cape Verde GPU. The Radeon HD 7870M and 7850M are equivalent to a significantly and very significantly underclocked desktop Radeon HD 7770 respectively, giving them TDPs of 35 and 45W. In the same way the Radeon HD 7770M and 7750M are equivalent to a more or less under-clocked Radeon HD 7750 with a TDP of between 25 and 35W.
Surprisingly, AMD has decided to confine the Radeon HD 7700M to PCI Express 2.0, at the same time saying that a PCI Express 3.0 with fewer lines allows us to reduce energy consumption. If this is the case, why hasn’t the Radeon HD 7750M benefitted? What’s the point of introducing this type of segmentation?
AMD is however emphasizing the use of several other technologies that allow these new graphics solutions to increase their energy yield: PowerTune to maximise the clock within the given thermal envelope, PowerGate to put any unused GPU blocks into idle (HD 7800M and 7700M only) and ZeroCore to shut the GPU down completely when the screen is on standby.
This isn’t all as this launch is also, at last, an opportunity for AMD to react to NVIDIA’s Optimus technology. To recap, Optimus allows you to juggle between an Intel IGP and a mobile GeForce, exclusively using the IGP display engine so that battery life isn’t reduced unnecessarily. AMD has taken up the Enduro solution, a development of Switchable Graphics, which was more limited and less supple in practice as it required the user to turn either the IGP or the GPU off instead of simply using the GPU to take up the slack on demanding tasks. Enduro naturally allows you to benefit fully from ZeroCore by switching the GPU off entirely when its help isn’t required.
Note that the technology is compatible both with the AMD APUs, A-Series and E-Series, and with Intel Sandy Bridge and Ivy Bridge CPUs. AMD doesn’t however say whether its partners will have to pay for a license to use it, as in the case of Optimus. When it comes to drivers, on Intel platforms a specific version including both Intel and AMD graphics drivers will be needed, which could have an impact on how often updates appear.
These new mobile Radeons easily give AMD the edge with respect to performance, with the Radeon HD 7970M and, more importantly, offer a reaction to the GK107, the little Kepler GPU that AMD has used in several GeForce 600Ms
. While on paper, the Radeon HD 7800Ms and 7700Ms seem to have a small advantage in terms of performance, it will be interesting to see how these solutions do in practice in terms of energy consumption!