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

Power Consumption: Windows 7 Versus Windows Vista

One of the first things I had wanted to test in our Core i5/Core i7 desktop launch piece was power consumption. Specifically, I was hoping to see a reduction in moving from Windows Vista to Windows 7. After all, Intel was touting its involvement in getting ideal core and core parking optimized for its Nehalem architecture, and the implication was that, at the very least, we’d see more cores idling more often.

It turned out that our PCMark Vantage testing did demonstrate slightly lower Windows 7 idle numbers, but because Windows 7 would ramp into Turbo Boost more quickly, it delivered better performance and higher power consumption than the same machine under Vista. We were told to wait for Clarksfield, where battery life would show the benefit of Microsoft’s and Intel’s collaborative work.

But first I wanted to chart a couple more Vantage runs. First up: our mobile Core i7-920XM-based system running fresh installs of Windows 7 and Windows Vista. As you can see, our results here mirror what we found in looking at the desktop Lynnfield configuration. Idle power consumption is lower in Windows 7, while load numbers are higher (along with performance).

I ran the same comparison on our mobile Core 2 Extreme setup and saw the same thing. It’s also interesting to note that idle and load power consumption fairly accurately reflects the 10W TDP increase of a Clarksfield setup. In essence, it’s going to take more battery to get the same run time out of a top-of-the-line mobile Core i7 versus a flagship Core 2 Extreme. 

  • 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.
    Reply
  • 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.
    Reply
  • 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.
    Reply
  • 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).
    Reply
  • @ 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.
    Reply
  • 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
    Reply
  • 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.
    Reply
  • _mrvtcng_
    I better read the articles from Techpowerup.com, it is more trustworthy. I dont like the articles from Tomshardware, it's only for noob who likes to be fooled.
    Reply
  • 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.
    Reply
  • 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.
    Reply