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Arrandale: 35W, 25W, And 18W

Mobile Core i7-920XM: Power Is The Price For Better Performance
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While Clarksfield is significantly more efficient than Bloomfield-equipped workstations, it’s not a solution that fans of thin-and-light form factors are really going to want (as you’ll see shortly, you can’t even get through a DVD movie on one battery charge).

The real mobile enabler of Intel’s Nehalem microarchitecture is going to be Arrandale, planned for a January 2010 launch. A dual-core chip armed with Hyper-Threading (and thereby able to address four threads at a time), Arrandale belongs to Intel’s 32nm Westmere family—the ‘tick’ to Nehalem’s ‘tock.’ The mobile processor family gets a scaled-back 4MB shared L3 cache, access to a dual-channel memory controller that steps official support down to DDR3-1066, and Turbo Boost technology. The more mainstream design will push power consumption from 45W down to 35, 25, and 18W models.

CPU (LGA 1156)
CPU Bin
Power
L3 Cache
DDR3
Graphics Turbo
Packaging
Arrandale Dual-Core
Power-Optimized Performance 3
35W
4MB
1066 MHz
500-766 MHz
rPGA
Arrandale Dual-CorePower-Optimized Performance 3
35W4MB
1066 MHz500-766 MHzBGA
Arrandale Dual-CorePower-Optimized Performance 2
35W3MB
1066 MHz500-766 MHzrPGA
Arrandale Dual-CorePower-Optimized Performance 2
35W3MB
1066 MHz500-766 MHzBGA
Arrandale Dual-CorePower-Optimized Performance 1
35W3MB
1066 MHz500-766 MHzrPGA
Arrandale Dual-CorePower-Optimized Performance 1
35W3MB
1066 MHz500-766 MHzBGA
Arrandale Dual-CoreLow-Voltage
25W
4MB
1066 MHz266-566 MHz
BGA
Arrandale Dual-CoreUltra-Low Voltage
18W
4MB
800 MHz
166-500 MHz
BGA


But those numbers alone don’t tell Arrandale’s whole story. As you no doubt already know, both upcoming Westmere-based processor families are actually two-chip packages consisting of a 32nm processor and 45nm graphics implementation (the platform’s memory controller resides on the graphics die this time around, and not on the processor itself). A basic evolution of Intel’s integrated GMA X4500HD, this upcoming generation should be notably faster thanks to significantly more memory bandwidth between itself and shared DDR3 system memory, though it’ll also feature 12 unified shaders to G45’s 10.

On its own, Arrandale’s graphics solution should be ample. Additionally, it’ll work in concert with a new set of 5-series chipsets that sport digital display connectivity (HDMI, DisplayPort, and DVI). Notebooks based on Arrandale and one of the new platforms will support a combination of two of those output technologies via a Flexible Display Interface linking CPU and chipset.

On top of the on-package graphics, Intel says it is enabling support for discrete graphics via Arrandale’s integrated PCIe 2.0 controller. What’s most interesting about this claim, however, is that add-on GPUs will be limited to first-gen transfer rates (it’s not clear whether this is due to lower signaling speeds or a narrower PCIe bus).   

Switchable Graphics

One of the most interesting features added to Intel’s GM45 chipset was switchable graphics—a hybrid technology consisting of an integrated graphics chipset and a discrete GPU. Ideally, ODMs would build notebooks with GM45 and an add-in graphics processor. Most of the time, under the Windows desktop, the platform would switch the add-in board off and rely on Intel’s reasonably-capable GMA4500MHD core. The potential savings was supposed to equal up to roughly an hour of battery life.

Unfortunately, Lenovo and Fujitsu were the only two builders to take advantage of switchable graphics. Whether the savings didn’t add up or the extra work required to implement switchable graphics was prohibitive, it just didn’t make sense to couple an integrated and discrete GPU in the same notebook. Instead, ODMs simply used PM45 platforms to enable add-in GPUs.

ATI supports switchable graphics through its Mobility Radeon HD 4000-series GPUsATI supports switchable graphics through its Mobility Radeon HD 4000-series GPUs

The story changes once you put graphics capabilities on the CPU package, though. Every 32nm Arrandale component has graphics built-in already, so any notebook also equipped with a discrete card has a basic hardware foundation in place for switchable graphics functionality. Thus, we expect switchable graphics to be a much more widely-adopted capability employed in Arrandale-based notebooks that also feature discrete graphics.

Of course, the challenge here is that switchable graphics isn’t an Intel-only technology. The company needs cooperation from ATI and Nvidia to enable support through drivers. As a result, Intel is saying that switchable graphics isn’t a critical launch feature, and it expects the requisite drivers to emerge four to eight weeks after launch. Then again, we've spoken with vendors who say switchable graphics remains a logistic challenge to implement; it might not end up being as compelling as Intel hopes after all.

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