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GeForce GTX 460M SLI: Mobile Gaming Value From AVADirect?

Nvidia's GeForce GTX 460M

With a die size less than half that of the GeForce GTX 480M, the GTX 460M’s 1.5 GB memory configuration could leave some users confused about its origins. A little poking around with GPU-Z helps shed some light on the internals.

Like the mobile parts that came before it, Nvidia sources its GTX 460M GPU from the desktop lineup, in this case the now-familiar GF106 previously found on the GeForce GTS 450. But how did the desktop card end up with 1.0 GB memory if capacities are limited to bus width multiplied by exponents of two?

Desktop vs Mobile GeForce Graphics
Desktop GeForce GTX 460Desktop GeForce GTS 450GeForce GTX 460M
Transistors1.95 billion1.17 billion1.17 billion
Engine Clock675 MHz783 MHz675 MHz
Stream Processors336192192
Texture Units563232
ROP Units321624
Compute Performance907 GFLOPS601 GFLOPS518 GFLOPS
DRAM Type1.0 GB GDDR5-36001.0 GB GDDR5-32061.5 GB GDDR5-2500
DRAM Interface256-bits128-bits192-bits
Memory Bandwidth115.2 GB/s57.7 GB/s60.0 GB/s
Module TDP160W106W65W

The desktop GeForce GTS 450 has been handicapped by Nvidia, in spite of what we were told at launch. The back-end was formerly limited to 16 ROP units and a 128-bit interface. The memory capacity difference now makes sense, because 128 x 8 equals 1024, and 192 x 8 equals 1536.

The added ROP units make it appear as though the GeForce GTX 460M might be a little more powerful than the desktop GeForce GTS 450, but a lower clock speed on an identical number of stream processors more than makes up the difference. The GTX 460M ends up short of the GTS 450, in spite of its extra bandwidth. But that’s probably fine with Nvidia since the desktop part often performs on par with the super-expensive GeForce GTX 480M.

Aside from what appears to be a huge performance deficit compared to the desktop GeForce GTX 460, the best reference point for GTX 460M performance could be the GTX 480M. With twice the memory bandwidth and twice the die size, Nvidia's GTX 480M undoubtedly costs more to manufacture than the GTX 460M. We checked the prices of two major vendors to find out how much a single-card to dual-card upgrade costs, in an effort to determine the cost-per-card built into each notebook.

Mobile Graphics Module Prices (Upgrade from Single to Dual GPU)
GeForce GTX 480MMobility Radeon HD 5870GeForce GTX 460M
Die Size529 mm²170 mm²238 mm²
Memory2 GB GDDR5-24001 GB GDDR5-40001.5 GB GDDR5-2500
Module Price$588$382$213

Before we even begin testing, the smaller part looks like it could provide a huge value benefit. The GeForce GTX 460M costs less than half the price of a GTX 480M, though higher yields on the smaller part could potentially account for the difference.