Original Link: http://www.anandtech.com/show/2785/the-new-macbook-pro-part-ii-lower-battery-life-under-vista-sata-issues



Last week I reviewed the new MacBook Pro. Not so much reviewed as tested battery life on it. I came away impressed. In three tests I managed to get between 5 and 8 hours of battery life out of the new 15” notebook. That’s longer than anything else at this performance/size level in my lab right now.

The previous generation MacBook Pro was good for about 3 - 5 hours. The less you do, the more you’ll find yourself closer to that 5 hour maximum. The more you do, the more you’ll find yourself at around 3 hours. Makes sense, no?

The new MacBook Pro works the same way. If you’re just typing in a window most of the time then you’ll find the new model, with integrated battery, will give you a crapton of battery life. Even using it like a productive, multitasking machine will yield close to 5 hours. Obviously your mileage may vary, but with 46% more battery capacity than the previous generation MacBook Pro you can expect at least that in battery life improvement from the new one.

A while ago, at the end of another MacBook review, I pointed out something odd. Battery life under OS X was much, much better than battery life under Vista:

  Wireless Internet Browsing DVD Playback Heavy Usage
MacBook Air (OS X) 4.98 hours 3.93 hours 2.7 hours
MacBook Air (Vista) 2.55 hours 2.05 hours 1.75 hours
Lenovo X300 (Vista) 2.82 hours 2.18 hours 1.68 hours

 

I attempted to create the same tests under Vista as I did under OS X and consistently found that the Mac notebooks offered much better battery life under OS X.

A few people asked how the new MacBook Pro fared under Windows. It lasted up to 8 hours under OS X, but how bad is the hit when going to Vista?

To find out I put together the same test I ran under OS X under a fresh install of Windows Vista x64 SP1. I even used Safari and iTunes for 64-bit Windows to keep the applications as similar as possible between the OSes.

I set Vista to the same brightness and power settings as OS X. I even chose the maximum power saving profile under Vista (my earlier tests used the Balanced profile). I ran the same wireless web browsing test I did for the new MacBook Pro review:

The wireless web browsing test uses the 802.11n connection to browse a series of 20 web pages varying in size, spending 20 seconds on each page (I timed how long it takes me to read a page on Digg and came up with 36 seconds; I standardized on 20 seconds for the test to make things a little more stressful). The test continues to loop all while playing MP3s in iTunes.
I only ran that test since it should give a good idea of the type of battery life degradation we can expect when going from OS X to Vista. If enough people would like to see more, I can always look at running a few more numbers but I believe this test alone should sum things up quite nicely.

Under OS X, this test yielded a battery life of 8.13 hours. The same test under 64-bit Windows Vista? Just over 6 hours:

New 15-inch MacBook Pro (73WHr battery) OS X 10.5.7 Windows Vista x64 SP1 Windows 7 RC1
Wireless Web Browsing (No Flash) Battery Life 8.13 hours 6.02 hours 5.48 hours

 

That’s nearly a 26% drop in battery life from OS X to Vista. When I first published these tests I spoke to a few PC OEMs to see if they had noticed any similar results. No one was willing to go on record but some OEMs did at least admit to seeing a ~20% difference between battery life in OS X and Vista.

The situation is apparently a bit better under Windows XP but not significantly. Even more depressing is the fact that Windows 7 doesn’t appear to make the situation any better. I still have a couple more hours in my Windows 7 run but I’ll update this page once I have the results. Right now it’s looking like ~6 hours for the new MacBook Pro under Windows 7 x64 RC1. Update: I finished the Windows 7 results and unfortunately it looks even worse than Vista. The even lower battery life is possibly due to earlier, unoptimized drivers for Windows 7. Either way, it doesn't look like Windows 7 is going to fix this issue.

Many have said that Sony and Lenovo are capable of offering similar battery life under Vista to what Apple can provide under OS X. We’ve been after both companies to get us hardware to help prove this point, but so far neither one has actually followed through. Needless to say, this is something we’re going to continue to investigate. I just figured you all might like to see updated results.



The SATA 3Gbps vs. 1.5Gbps Issue

All unibody MacBook/MacBook Pros use NVIDIA’s GeForce 9400M chipset. The chipset includes native support for up to six SATA ports running at 3.0Gbps (300MB/s max transfer rate). Here’s a copy of OS X’s system profiler showing 3.0Gbps as the interface speed on the previous generation MacBook Pro:


3 Gigabit...only on the first unibody MacBook Pro

Unfortunately, the current version of the MacBook Pro appears to only support 1.5Gbps SATA. I’m not sure whether this is an OS, drive or hardware problem, but your drive is limited to transfer rates of 150MB/s. For most laptop drives, this isn’t a problem. Your 5400RPM SATA drive just isn’t going to be moving anything at 150MB/s. The real problem lies with high performance SSDs.

Let’s look at the read/write performance of the three top SSDs on the market today: the Intel X25-M, the OCZ Vertex and the Corsair P256:

New 15-inch MacBook Pro (73WHr battery) 4KB Random Read 4KB Random Write 2MB Sequential Read 2MB Sequential Write
Intel X25-M 54.2 MB/s 22.2 MB/s 230 MB/s 71 MB/s
OCZ Vertex (Indilinx) 34.9 MB/s 6.55 MB/s 256 MB/s 137 MB/s
Corsair P256 (Samsung) 29.1 MB/s 0.78 MB/s 207 MB/s 178 MB/s

 

You’ll see four categories of performance: random read, random write, sequential read and sequential write speed. All four categories matter to the performance of your hard drive but some are more noticeable than others depending on what you do.

Random read/write performance actually contributes to your system feeling fast more than anything else. These are the sorts of transactions that happen when you’re launching applications or searching for files. Sequential read/write transactions happen when you’re copying large files to/from your drive. The latter is less common than the former for most users but that’s why you don’t see the 1.5Gbps issue really impacting real world performance on the new MacBook Pro.

All three of the SSDs in the table above would be interface limited on the new MBP because of their high sequential read speeds. If you were copying large files from the SSD in your MacBook to a similarly fast device, the transfers could take longer. I doubt the performance difference would be significant or noticeable in real world notebook usage, but it doesn’t change that there’s no reason to take a step backwards like that. In the coming years we’ll see more drives that can consistently break 150MB/s; Apple artificially limiting performance today would just hinder progress.

I’m not sure what the issue is since the 9400M does support 3Gbps SATA. Perhaps it could be one of the mystery optimizations Apple did to increase battery life well beyond reasonable expectations? Or perhaps it’s just an issue with the firmware and something that will be corrected in the near future. It's worth noting that the version of OS X 10.5.7 that ships with the new MacBook Pro is a different build than the one everyone else gets to download.

It’s something to keep an eye on and I’ve already sent out some probes trying to gather more on the issue.

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