Mobile Core i7-920XM: Power Is The Price For Better Performance

Arrandale: 35W, 25W, And 18W

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.

Swipe to scroll horizontally
CPU (LGA 1156)CPU BinPowerL3 CacheDDR3Graphics TurboPackaging
Arrandale Dual-CorePower-Optimized Performance 335W4MB1066 MHz500-766 MHzrPGA
Arrandale Dual-CorePower-Optimized Performance 335W4MB1066 MHz500-766 MHzBGA
Arrandale Dual-CorePower-Optimized Performance 235W3MB1066 MHz500-766 MHzrPGA
Arrandale Dual-CorePower-Optimized Performance 235W3MB1066 MHz500-766 MHzBGA
Arrandale Dual-CorePower-Optimized Performance 135W3MB1066 MHz500-766 MHzrPGA
Arrandale Dual-CorePower-Optimized Performance 135W3MB1066 MHz500-766 MHzBGA
Arrandale Dual-CoreLow-Voltage25W4MB1066 MHz266-566 MHzBGA
Arrandale Dual-CoreUltra-Low Voltage18W4MB800 MHz166-500 MHzBGA

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 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.

Chris Angelini
Chris Angelini is an Editor Emeritus at Tom's Hardware US. He edits hardware reviews and covers high-profile CPU and GPU launches.
  • anamaniac
    Great article as always Chris.

    And for switchable graphics, how about the integrated for 2D mode and discrete for 3D mode?
    I'd think that'd be the best way.

    I appreciate you doing the thorough power testing. Nice to see what I can expect from these.
  • cangelini
    Thanks much anamaniac--the challenge is that switching between integrated and discrete isn't completely seamless. In other words, you'd have to click/push a button to make it happen, according to the guys I've talked to, even with Arrandale.
  • El_Capitan
    Nice review. I've been looking into notebooks for a while now, and am wondering why anyone would get the Mobile Core i7 720XM over a D900F with a W3520 or i7 920? Or the i7 920XM over a D900F with an X5550 or i7 975? The only reason I can think of is the weight of the notebook (and maybe a little more cost).

    1. Power over battery-life. The only option for me to have something that powerful is to work when I'm away from home or the office. I do this on occasion, and rarely am I not plugged into a power source. I sleep on the plane, and if I want to watch a movie, I've got my iPod Touch (I read when I'm awake, anyway). Those looking to get a notebook like these aren't worried about battery-life.

    2. Out-of-warranty usage. I go through notebooks about 1-2 years. Not because they break (all of mine still work... mostly), but because they're out of date for what I need them to do. I could upgrade the CPU's on some, but for a lot of money for just a little gain. I've sold most of my older laptops since "converting" them to desktops also costs more than just building a desktop with desktop CPU's.

    The best thing about the D900F? Once you're done with it, you've got a desktop CPU to build a desktop with. Mobile CPU's? They go out of date pretty fast.

    They should just stop making power-hungry mobile CPU's and just find ways to make desktop CPU's portable... but then they wouldn't be able make all that dough on the mobile market.
  • anamaniac
    Brandenburgh_ManReading articles on Tomshardware, Anandtech, ExtremeTech, etc. is getting to be such a fucking pain in the ass. It's bad enough that the articles are divided into 20 pages just so they can show 100 advertisements per article, but scrolling through a page of text is like walking through a fucking minefied. If your mouse cursor accidentally rolls over a word containing a hot link, yet another bullshit advertisement pops up, blocking your view of a full paragraph's worth of text. And quite often you can't move these ads or close them without reloading the whole fucking page. Jesus Christ!Use AddBlockerPlus and stop bitching.
    cangeliniThanks much anamaniac--the challenge is that switching between integrated and discrete isn't completely seamless. In other words, you'd have to click/push a button to make it happen, according to the guys I've talked to, even with Arrandale.Damn... the simplest things just can't be easy, can they?
    Though hopefully the dual cores GPU holds up well enough that we don't need a discrete (and for those that would require a discrete in the first place may be going for a quad core... assuming any affordable i7 laptops come out).
  • @ Brandenburgh_Man

    That's adware that's infected your system. When you scroll over words like PC of HP or Dell, it's adware highlighting it, not the site. Time to disinfect.
  • scook9
    Switchable Graphics is not a new idea necessarily....Alienware has been doing this in laptops for a while. The Area-51 m15x was the first with it I believe - It has an Nvidia discrete GPU and the Intel IGP

    The M17x "All Powerful" also has this feature, using either the GTX 280m SLI or 9400m as needed for Power or Battery life. I have an M17x with 280m SLI and a QX9300 and when I switch to the 9400m I can enjoy about 3.5 hours of battery life with regular usage if the screen is dimmed. I was able to watch a complete blu-ray movie with the 9400m accelerating playback and then play solitaire for 45 minutes with a full charge all off battery on a plane.

    I am looking forward to someone figuring out how to get SLI AND the mobile i7 into a laptop/desktop replacement but so far I don't think it is going to happen due to that just being too much power used at one time.

    Outstanding review and exactly what I was looking for to get a reference point on these new CPUs
  • Doesn't look to be a very good product, IMHO. Way too much TDP, for what doesn't amount to enough performance gain. Laptops that run too hot and suck too much power will always be subject to reliability problems.

    It may work fine if you never do anything CPU intensive, but I'm sure it probably hits in the neighborhood of 100c if you do something CPU intensive like compiling a Linux kernel or transcoding video. If you never do anything CPU intensive, then you don't need this anyways.
  • _mrvtcng_
    I better read the articles from, it is more trustworthy. I dont like the articles from Tomshardware, it's only for noob who likes to be fooled.
  • godwhomismike
    Why not review the Mobile Core i7-720QM instead of the i7-920XM, since 90%+ of your readers will likely only be able to get a 720QM or an 820QM? I'll admit the 920XM is an impressive processor, but in this economy, there are very very few of us who have the money to buy a computer which has a $1000+ CPU in it.
    I look forward to an article that will compare the 720QM vs the 820QM, and see if the extra cache and speed make much of a difference.
  • masterasia
    WOW! GTX 260m with i7 920XM sounds really good. Add an Intel X25-E SSD and it would be totally awesome. It's too bad that it'll probably cost like $3000 or more.

    What does AMD have up their sleeves to counter this? Nothing probably. I've always hated AMD mobile processors because they use so much power and get so little performance. i7 mobile's 45 and 55 watts isn't too bad because the performance is out of this world.