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Week in Tech: Nvidia Laptop Graphics Update

Get yourself a gaming lappie

Yes, we've done the Nvidia Maxwell graphics thing already. As a desktop GPU, the new GeForce GTXs 750 and 750 Ti aren't all that exciting. But the same Nvidia GM107 chip rebadged Nvidia GeForce GTX 860M and stuffed into a laptop? Suddenly, things get a whole lot more interesting. The specifics aren't official yet. But it looks like GM107 might just deliver twice the performance for the same power budget as its predecessor and that's pretty exciting for thin-and-light gaming lappies. And remember, this is just the beginning for Maxwell – the arrival of second-gen 20nm Maxwell mobile GPUs could be spectacular. While we're here, I thought a beginners guide to mobile GPUs would be useful for some of you. What with all the branding shenanigans both Nvidia and AMD get up to in the mobile space, keeping track of what's actually on offer isn't always easy.

A bit like last week's look at the Intel Haswell refresh, we're officially dealing with rumour here. (Since I wrote this official details have confirmed most of what we're about to cover, see update below.) But for the most part it's hardly speculative stuff. What we know for sure is that the first Maxwell GPU from Nvidia is codenamed GM107. In gaming terms, it's a low-end chip and it's been launched in desktop form as the GeForce GTXs 750 and 750 Ti.

We can also infer that it's likely going-on-guaranteed that GM107 will turn up in laptops. Because that's what happens. Why? Here's that quick beginners guide to mobile GPUs. Nvidia and AMD don't make dedicated gaming GPUs for laptops. They use the same chips found in desktop boards, albeit usually running different specs, including clocks, voltages or even parts of the chip fused off.

Nvidia Maxwell: A bit 'meh' on the desktop to date, but has the makings of 'oh my' as a mobile GPU

Mobile GPUs are also typically taken from the highest quality bins. In other words, chips are cut from the big, round wafers of silicon that come out of the manufacturing fabs and then tested for various operating properties. There can be quite a bit of variance in terms of stability at given voltages and clockspeeds and operating temperatures. I'm not sure if every chip cut from a wafer is tested for clocks and temps or a sample from each wafer runs the gauntlet and the remainder are assumed to be cut from the same cloth. But I do know all chips are tested for basic functionality, so perhaps it's the former.

Either way, the cream of the crop tend to be siphoned off for mobile usage where temps and voltages are really critical. As it happens, Nvidia's Maxwell is being pitched as the first GPU architecture designed for mobile first. If you want, then, you can view GM107 as a mobile chip that will also be used in desktops.

Anyway, thanks to some plausible looking posts on the Notebookreview forum, we have a pretty good idea of what GM107 will look like in notebooks. It'll be known as the GeForce GTX 860M. Unfortunately, both Nvidia and AMD have been playing silly buggers with mobile GPU branding for a while.

In simple terms, the branding no longer aligns across the two platforms. A desktop Geforce GTX 750 is based on an entirely different chip or ASIC from the mobile 750M. As a rule of thumb, take the biggest, hairiest desktop GPU and discard it. Then take the second-rung desktop GPU and rebrand it with the discarded GPU's name adding an 'M' for good measure. Now you have the top mobile GPU. Rinse and repeat as you drop down the product range.

It wasn't always like this, more's the pity. The high point was probably the GeForce Go 7800 GTX which was a gnat's chuff from matching the desktop 7800GTX. For once, desktop and mobile graphics were at near parity.

Fancy a Razer Blade with double the graphics performance of the current model?

Whatever, a handy website for uncovering just what you're dealing with for any given mobile GPU is Notebookcheck.net. It's not completely infallible. And it's worth noting that implementations of any given mobile graphics chipset can very dramatically from one laptop to the next. But it is pretty comprehensive and a very useful source of information including a massive array of benchmark results with a wide variety of games, the better to give you at least an idea of what to expect from any mobile GPU.

Back to the new 860M it looks like we're talking 640 shader cores (yay) and a 128-bit memory bus (boo). Remember, that's 640 Maxwell-style shader cores, so in raw performance terms arguably equivalent to 800-plus shaders from the Kepler generation.

Anyway, the really fun bit and where things do become a little speculative is power consumption. The 860M is thought to be in roughly the same ballpark as the old 660M GPU. So we're talking about a chip with power consumption around the 40W mark.

Gigabyte's P34G is one of relatively few thin-and-light gaming lappies

Given the early performance numbers it seems to be clocked at roughly 900MHz and kicks out roughly the same performance as the much more power hungry 770M. If you're wondering why I haven't mentioned what seems to be the obvious comparison GPU, the 760M, it's because that chip is based on the GK106 GPU rather than the GK107, the latter being the real predecessor to GM107.

At this point I need to apologise for all these ghastly code names and reduce this down to some take-homes that actually mean something worthwhile. In really simple terms, what this all means is that thin-and-light laptops are just about to get twice as fast for gaming. Well, the ones lucky enough to have a Maxwell GPU, at least.

A properly gameable 14-inch thin-and-light has always been a prime form factor for me and GM107 looks like the chip that might just deliver. I reckon it'll just about have the minerals for 1080p gaming at highish quality settings. Think of it as being roughly on a par with the new consoles for pure graphics grunt. Nice.

And remember, Nvidia has achieved all this with existing 28nm tech. When it starts knocking out 20nm second-gen Maxwell chips, odds are we are likely to see some spectacular mobile GPUs. Take the 14-inch Razer Blade and its GTX 765M GPU, aka GK106. Then imagine a GM106 chip (or possibly GM206 if that's how the nomenclature rolls for 20nm Maxwells) with double the performance in the same power budget. Yes please.

Oh, no, not another Clevo clone?! Yup, it's the 13.3-inch W230ST

The potential snag to all this is pricing. Gaming notebook pricing has proven frustratingly firm over the years and I suspect the 860M will be priced in a manner that reflects its impressive performance rather than the entry-level status of the GM107 ASIC. So my holy grail of a gameable 14-inch thin-and-light with a half decent screen for about £500 will probably remain tantalisingly out of reach.

The closest thing I'm aware of right now is probably something based on the 13.3-inch Clevo W230ST, which can be had specced with a low-end Core i3 plus GTX 765M, a small 120GB SSD and an IPS 1080p screen, all for about £700 from the likes of PC Specialist. I've never been a huge fan of Clevo systems, however, and I doubt this one breaks from the Clevo tradition of being a functional but unattractive brick.

P.S. If it feels like the graphics coverage has been a bit Nvidia centric of late, stay tuned for some AMD insights in the coming weeks.

Since I wrote this further details have emerged concerning the broader Geforce 800 Series mobile GPUs. They're largely in line with everything above with one exception. There will apparently be two 860M GPUs, one as detailed here and based on Maxwell tech, another based on the old GK106 Kepler chip. This is completely baffling. As one commenter on Anandtech says, it represents a new low in GPU spec obfuscation and is utterly deplorable.

It's also worth nothing that the 860M is the only model in the new line up based on Maxwell technology, so we are probably some time from seeing any second-gen 20nm Maxwell chips.

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Jeremy Laird