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GeForce GTX 880M, 870M, And 860M: Mobile GPUs, Tested

Introducing The GeForce GTX 800M-Series

Sometimes it feels like desktop gamers get all of the cool toys, while the notebook guys get hand-me-downs. Rare is it that a new graphics processor debuts in the mobile space. There's just so much more involved when you bring technology down into limiting form factors and power budgets. 

It really comes as no surprise, then, that we're on a third generation of mobile products with Nvidia's GK104 in the mix. After all, that was quite the efficient GPU when it launched more than two years ago. Today it remains viable as the engine driving Nvidia's highest-end GeForce GTX 800-series modules. Let's take a look at some of the brand's specs:

Nvidia GeForce GTX 880M Comparative Specs
Desktop GTX 780Notebook GTX 880MNotebook GTX 780MNotebook GTX 680MXDesktop GTX 680
Texture Units192128128128128
Full Color ROPs4832323232
Graphics Clock MHz (Boost)863 (900)954 (993)771 (797)7201006 (1058)
Texture Fillrate166 Gtex/s122.1 Gtex/s105.3 Gtex/s92.2 Gtex/s128.8 Gtex/s
Memory Clock1502 MHz1250 MHz1250 MHz1250 MHz1502 MHz
Memory Bus384-bit256-bit256-bit256-bit256-bit
Memory Bandwidth288 GB/s160 GB/s160 GB/s160 GB/s192 GB/s
Die Size551 mm²294 mm²294 mm²294 mm²294 mm²
Transistors (Billion)7.13.543.543.543.54
Process Technology28 nm28 nm28 nm28 nm28 nm

The original GeForce GTX 680M appeared to be an underclocked GeForce GTX 670; Nvidia quickly augmented performance through an updated GeForce GTX 680MX.

Here's the thing: you have a certain amount of freedom to ramp up clock rate and voltage on a graphics card designed for a desktop PC. Transitioning to a mobile form factor limits flexibility immensely. Sure, we've seen some huge desktop replacements with big graphics power inside. But both AMD and Nvidia are trying to enable technologies that make maximum performance available when it's needed, then scaling back as much as possible when it isn't.

Like the GeForce GTX 780M, Nvidia's recently-introduced 880M lifts all eight SMX units from the GK104 processor. Whereas the 780M operated at a 771 MHz base clock rate, however, the 880M starts at 954 MHz. Nvidia gives it a typical GPU Boost rating of 993 MHz. Both of those figures are far closer to the desktop GeForce GTX 680 (even if the new mobile flagship carries over the 780M's slower GDDR5-5000 data rate).

At least on the specification side, there's little more than this frequency increase to discuss. Memory density doubles, but without the large jump in GPU spec needed to push similarly-increased display resolutions. So, we have to hope that the latest GK104s coming out of TSMC are running faster at lower voltages to keep power and heat under control.

Nvidia GeForce GTX 870M Comparative Specs
Desktop GTX 770Notebook GTX 870MNotebook GTX 770MNotebook GTX 670MXDesktop GTX 670
Texture Units1281128080112
Full Color ROPs3232242432
Graphics Clock MHz (Boost)1046 (1085)941 (967)706 (797)600915 (980)
Texture Fillrate134 Gtex/s105.4 Gtex/s64.9 Gtex/s48 Gtex/s102.5 Gtex/s
Memory Clock1753 MHz1250 MHz1002 MHz700 MHz1502 MHz
Memory Bus256-bit192-bit192-bit192-bit256-bit
Memory Bandwidth224 GB/s120 GB/s96 GB/s67.2 GB/s192 GB/s
Die Size294 mm²294 mm²221 mm²221 mm²294 mm²
Transistors (Billion)3.543.542.542.543.54
Process Technology28 nm28 nm28 nm28 nm28 nm

Moving down the stack, Nvidia's GeForce GTX 870M gives mobile users the same seven SMX units from the desktop GeForce GTX 670. The previous two generations (GeForce GTX 770M and 670MX) were both based on GPUs with five SMX blocks instead.

The new GeForce GTX 860M offers an even bigger surprise, also utilizing the GK104 graphics processor. In this implementation, however, it includes six functional SMX units, yielding 1152 CUDA cores, similar to Nvidia's GeForce GTX 760 card. Of course, it operates at far lower base and typical GPU Boost frequencies, and is complemented by slower GDDR5-5000 memory on a narrower 128-bit bus. But that's all in the name of pulling power lower and making the 860M work in a line-up of other GK104-driven modules.

Nvidia GeForce GTX 860M Comparative Specs
Desktop GTX 760Notebook GTX 860MNotebook GTX 765MNotebook GTX 660MDesktop GTX 660
Texture Units9696643280
Full Color ROPs3216161624
Graphics Clock MHz (Boost)980 (1033)797 (915)797 (863)835980 (1033)
Texture Fillrate94 Gtex/s76.5 Gtex/s54.4 Gtex/s26.7 Gtex/s78.4 Gtex/s
Memory Clock1502 MHz1250 MHz1002 MHz1250 MHz1502 MHz
Memory Bus256-bit128-bit128-bit128-bit192-bit
Memory Bandwidth192 GB/s80 GB/s64 Gb/s80 GB/s144.2 GB/s
Die Size294 mm²294 mm²221 mm²118 mm²221 mm²
Transistors (Billion)3.543.542.541.32.54
Process Technology28 nm28 nm28 nm28 nm28 nm

There's a caveat, though. Nvidia specifies its GeForce GTX 860M with two completely different GPUs. The same we received, of course, employs GK104. But you'll also find GeForce GTX 860Ms based on the GM107 found in the GeForce GTX 750 Ti. That’s kind of like reserving a 16-hand gelding for your day at the ranch and arriving to find a Shetland pony.

Of course, it's hard to say how both versions compare without having them both on-hand for testing. The GM107-based version is configured to run at similar clock rates as the card we tested in GeForce GTX 750 Ti Review: Maxwell Adds Performance Using Less Power, albeit with a slightly lower memory frequency. Meanwhile, GK104 is pared way back.

Without performance data to look at, we have to hope that Nvidia is realizing similar results from GK104 and GM107. If it's not, the most we can do right now is make you aware of the two different versions of GeForce GTX 860M.

Thomas Soderstrom
Thomas Soderstrom is a Senior Staff Editor at Tom's Hardware US. He tests and reviews cases, cooling, memory and motherboards.