Apple's MacBook Pro with 128GB SSD: Performance and Battery Life Investigated
by Anand Lal Shimpi on April 15, 2008 4:20 PM EST- Posted in
- Mac
Better Battery Life? Not Necessarily
Hitachi lists the read/write power of the 5K250 that comes in the MacBook Pro as 1.7W on average. Idle power is even lower obviously. Memoright doesn’t provide similar specs on the MR25.2-128S but the top of the drive already tells an interesting story: 600mA at 5V, or 3W. It looks like in the quest for greater performance, the Memoright drive actually consumes more power than a mechanical disk drive. While Flash memory should have no problems running at 3.3V, I suspect that the FPGA and PATA-SATA bridge both require a 5V input which is why the drive uses 5V power from the SATA power connector and not 3.3V.
With potentially greater power usage, it doesn’t look like we’ll be gaining any battery life from the SSD. To confirm, we ran the same battery life tests we have been using in our recent MacBook Air and MacBook Pro reviews:
| Battery Life in Hours (Higher is Better) | MacBook Pro (Hitachi 5400RPM) | MacBook Pro (Memoright SSD) |
| Wireless Internet Browsing + MP3 Playback | 5.13 hours | 5.0 hours |
| DVD Playback | 3.88 hours | 3.58 hours |
| Heavy Downloading + XviD Playback + Web Browsing | 3.38 hours | 3.37 hours |
The wireless browsing test shows the mechanical disk offers a slight battery life advantage of around 8 minutes over the SSD system. While losing 8 minutes of battery life isn’t tremendous, the point is that battery life doesn’t improve any.
The DVD playback test paints the SSD’s battery life in the worst light; the system equipped with a mechanical disk outlasts it by around 8%. In the case of the MacBook Pro, that 8% translates into 18 minutes of battery life.
Our final test shows no difference between the mechanical and SSD drive.
It’s worth noting that how the SSD fares really depends on the reference point. Had we used an older, higher power mechanical disk the situation might have been different. A quick look at the specs for the 7200RPM drive that Apple offers on its MacBook Pro shows that despite a faster spindle speed, power consumption would increase to 2.3W, still lower than the Memoright drive.
Memoright doesn't list more detailed power specs for its drive so it's possible that the difference is closer, but without a doubt the SSD doesn't offer any power advantages in this case. The battery life tests provide an important distinction, as we saw battery life increase in the MacBook Air but decrease here. It just goes to show you that simply switching to a SSD won't necessarily improve battery life, it depends on what you're switching from and what you're switching to.
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Denithor - Wednesday, April 16, 2008 - link
When will these become available/affordable for desktop use? HTPC comes immediately to mind, but I would like one for my gaming rig if it yields a "snappier" system for a moderate cost.mindless1 - Friday, April 18, 2008 - link
You must be kidding. Minimal to no gain in sequential access, improvement primarily in random access, limited capacity, and extreme price per GB make this about the worst choice possible for a HTPC.Regardless, if that's what you want go ahead and do it, drive rail adapters to use 2.5" in 3.5" bays are not expensive or hard to find. You could even squeeze two or three drives into one 3.5" bay so you have a HTPC with $12,000 spent on storage instead of a $80 mechanical drive.
just4U - Wednesday, April 16, 2008 - link
Is it possible to instal Windowso n a flash drive. You know, one of those 16/32 meg jobs. This article has got me curious.. :)strikeback03 - Thursday, April 17, 2008 - link
I assume you mean 16/32GB, and yes, I believe I saw instructions for that over at mp3car.com.mindless1 - Friday, April 18, 2008 - link
Instructions? Not a complex process.1) Buy CF3 or CF4 spec'd CF card and CF-IDE adapter. CF card performance is lower than on a good SSD so staying with PATA/IDE interface is not a bottleneck.
2) Plug card into adapter, plug adapter into system.
3) You're done, there is now no difference beyond having mechanical drive instead, although if SSD is not using SLC flash chips you might want to decide how to limit # of writes to it from pagefile, temporary browser files, etc.
strikeback03 - Friday, April 18, 2008 - link
I just glanced at the instructions as I am not building a carputer yet, but IIRC a lot of it was optimizing the pagefile and other little writes.Nihility - Wednesday, April 16, 2008 - link
That needs to be fixed, no reason for flash to take more power than a hard drive, maybe they can power off some of the flash that is unused until it's needed? If it doesn't even increase battery life then what's the point? Resilience and random seek times are nice but battery life is the main concern on a mobile platform.mindless1 - Friday, April 18, 2008 - link
It's the controller, bridge and cache that use the power, these flash chips don't have to be recharged.Keep in mind that while battery life is important, and power consumption of an SSD will go down over time, they still aren't one of the larger consumers of power. Ultimiately if runtime is most important the area to focus on is designers who mistakenly assume a smaller device footprint is more important than runtime, thus squeezing in a smaller battery (capacity).
iwodo - Tuesday, April 15, 2008 - link
Intel 's SSD promise doubling the performance of current SSD Drive. I cant wait to see it.I wonder would the ARM7 chip be the limiting factor here?
skiboysteve - Tuesday, April 15, 2008 - link
"two areas of inefficiency: the drive isn't a native SATA device and it uses a FPGA instead of a custom IC for some functions."this is incorrect. using an FPGA instead of a custom IC makes no difference in performance whatsoever. the difference is in cost. there is a lot of research into cost/benefit of using an FPGA instead of a custom ic and it all boils down to volume. obviously, they dont have high enough volume to necessitate a custom IC.
but, an fpga configured to behave exactly like what your custom IC would behave like ... are the same thing. only difference again, is price.
some point might astutely point out that a custom IC can be clocked higher, but i very much doubt that advantage is applicable here.