Intel’s Sandy Bridge i7-2820QM: Upheaval in the Mobile Landscape
by Jarred Walton on January 3, 2011 12:00 AM EST- Posted in
- Laptops
- Intel
- Sandy Bridge
- Compal
All the Performance, and Good Battery Life As Well!
We’ve just finished showing that CPU and GPU performance has basically more than doubled compared to last year’s Arrandale offerings. That’s great news, but what happens to battery life? We’ve got 35W TDP Arrandale parts compared to a 45W TDP Sandy Bridge quad-core; doesn’t that mean battery life will decrease by around 25%? The answer is happily no; as we’ve point out in the past, TDP isn’t really a useful measurement of power requirements. All the TDP represents in this case is the maximum amount of power Sandy Bridge should draw. So worst-case battery life under full load might drop, but the real question is going to be what happens under typical workloads.
Intel’s use of power gating and variable clock speeds is put to good use, with the result being battery life that is nothing short of exceptional when compared to previous generation products. We’ve seen ULV and Atom netbooks and ultraportables get battery life into the 8+ hour range, but such designs have always required serious compromise in the performance department. SNB certainly won’t beat out Atom for pure battery life, but that doesn’t mean it’s a power hog. Our Compal test system comes with a 71Wh battery, which is larger than what we’ve seen in many 15.6” and smaller designs but still reasonable for a 17.3” chassis. Here are the results of our standard battery life testing.
Yes, those figures are accurate. Best-case, running at 100nits, quad-core Sandy Bridge still lasted nearly eight hours on a single charge! What’s more interesting is that our standard Internet battery life test that loads four pages with Flash ads every sixty seconds still checks in just shy of seven hours. Finally, H.264 playback also comes in at the top of our charts, providing more than four hours of demanding video playback. If 240 minutes of content off your HDD/SSD isn’t enough, we also were able to watch a Blu-ray disc and still get 220 minutes of 35Mbit VLC playback. Wow!
So Sandy Bridge comes out on the top of the above charts, but we didn’t include some of the other long battery life alternatives. Just to put things in perspective, ASUS’ U30JC—with an SSD and an 84Wh battery—has long been our king for matching reasonable performance with long battery life. It managed 588 minutes idle, 476 minutes Internet, and 254 minutes H.264 playback. That’s 25% more idle life, but only 14% better Internet and actually slightly lower H.264 battery life, and you need to factor in the 18% higher capacity battery and 13.3” (versus 17.3”) LCD.
We have to wonder just how small of a form factor manufacturers can manage to cram the quad-core Sandy Bridge into. Idle and low usage power requirements are clearly very good, but with maximum TDP still at 45W the chassis needs to be able to handle the heat. We’d really love to see some 14” designs with quad-core CPUs, and the icing on the cake would be sticking a reasonably fast discrete GPU with graphics switching technology into the case as well. Intel doesn’t have any LV/ULV quad-core parts listed—yet!—so we may have to wait for ultraportable quad-core laptops, but certainly 15.6” designs should be able to combine SNB with reasonably fast Optimus GPUs to provide an optimal blend of performance and mobility.
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mtoma - Monday, January 3, 2011 - link
Something like Core i7 1357M could make Win 7 tablets temporarily viable. Remember that in the ultra portable space the big words are: multitasking, dual core processors (like Cortex A9). So, realistically, we need ULV dual-core Sandy Bridge.JarredWalton - Monday, January 3, 2011 - link
The i7-640M runs at 1.2GHz minimum and 2.26GHz maximum. The i7-2657M runs at 1.6GHz minimum and 2.7GHz maximum. (Actually, minimum on all the Core 2nd Gen is 800MHz when you aren't doing anything that needs more speed.) That would be 33% faster base speed and up to 19% higher max speed, just on clock speeds alone. However, you forgot to factor in a round 20-25% performance increase just from the Sandy Bridge architecture, so you're really looking at anywhere from 19% (bare minimum) to as much as 66% faster for normal usage, and things like Quick Sync would make certain things even faster.DanNeely - Monday, January 3, 2011 - link
You've got a limited range of TDP that any given architecture will be good in. According to Intel (at the time of the atom launch) things start getting rather ragged when the range gets to 10x. Until Core2 this wasn't really an issue for Intel because the p3 and prior's top end parts had sufficiently low TDPs that fitting the entire product line into a single architecture wasn't a problem. It didn't matter much in the P4 era because the Pentium-M and Core 1 were separate architectures and could be tuned so its sweet spot was significantly lower than the desktop P4. Beginning with Core2 however Intel only had a single architecture. The bottom tier of ULV chips suffered due to this, and on the high end the fact that overclocking (especially voltage OCing) was very poor on the performance gain/increased power consumption scale.The atom is weak as you approach 10W because it was designed not as a low end laptop part (although Intel is more than willing to take your money for a netbook); but to invade ARM's stronghold in smartphones, tablets, and other low power embedded systems. Doing that requires good performance at <1W TDP. By using a low power process (instead of the performance process of every prior Intel fabbed CPU) Moorestown should finally be able to do so. The catch is that it leaves Intel without anything well optimized for the 10-15W range. In theory the AMD Bobcat should be well placed for this market, but the much larger chunk of TDP given to graphics combined with AMDs historic liability in idle power make it something of a darkhorse. I wouldn't be surprised if the 17W Sandybridge is able to end up getting better battery life than the 10W Bobcat because of this.
Kenny_ - Monday, January 3, 2011 - link
I have seen in the past that when Mac OS X and Win 7 are run on the same machine, Mac OS X can have significantly better battery life. Is there any chance we could see what Sandy Bridge does for battery life under Mac OS X?QChronoD - Monday, January 3, 2011 - link
This was a test machine that intel cobbled together. Give it a few weeks or months after some retail machines come out, and then I'm sure that someone in the community will have somehow shoehorned OSX onto one of the machines. (Although I don't know how well it would perform since they'd probably have to write new drivers for the chipset and the graphics)cgeorgescu - Monday, January 3, 2011 - link
I think that in the past we've seen MacOS and Win7 battery life comparison while running on the same Mac, not on the same Acer/Asus/Any machine (cause MacOS doesn't run on such w/o hacks). And I suspect Apple manages better power management only because they have to support only few hardware configurations (so doing optimizations especially for that hardware), it's a major advantage of their business model.It's like with the performance of games on Xbox and the like... The hardware isn't that impressive but you write and compile only for that configuration and nothing else: you're sure that every other machine is the same, not depending on AMD code paths, smaller or larger cache, slower or faster RAM, that or the other video card, and so on...
Aside power management in macs, to see what Sandy Bridge can do under MacOS would be frustrating... You know how long it takes until Jobs fits new stuff in those MBPs. Hell, he still sells Core2 duo.
Penti - Monday, January 3, 2011 - link
Having fewer configurations don't mean better optimized graphics drivers they are worse. Having only intel doesn't mean the GCC compiler only outputs optimized code. It's a compiler AMD contribute to among others and there's no such thing as AMD code paths, there is some minor difference in how it manages SSE but that's it. Most is exactly the same and the compiler just optimizes for x86 not a brand. If it supports the same features it is as optimized. Machine Code is the same. It's not like having a cell processor there.Power management is handles by the kernel/drivers. You can expect SB MacBooks in like this summer. Not too long off. And you might even be seeing people accepting Flash on their macs again as Adobe is starting to move away from their archaic none video player work flow. With 10.2 and forward. Battery/Power management won't really work without Apples firmware though. But you are simply not going to optimize code on a OS X machine like a console, your gonna leave it in a worse state then the Windows counterpart. Apple will also be using C2D as long as Intel don't provide them with optimized proper drivers. It's a better fit for the smaller models as is.
mcdill the pig - Monday, January 3, 2011 - link
Perhaps the issue is more the Compal's cooling system but those max CPU temps (91 degrees celsius) seem high. It may also be that the non-Extreme CPUs will have lower temps when stressed.My Envy 17 already has high temps - I was looking forward to SB notebooks having better thermal characteristics than the i7 QM chips (i.e. no more hot palmrests or ball-burning undersides)....
JarredWalton - Monday, January 3, 2011 - link
This is a "works as designed" thing. Intel runs the CPU at the maximum speed allowed (3.1GHz on heavily threaded code in this case) until the CPU gets too warm. Actually, funny thing is that when the fan stopped working at one point (a cold reboot fixed it), CPU temps maxed out at 99C. Even with no fan running, the system remained fully stable; it just ran at 800MHz most of the time (particularly if you put a load on the CPU for more than 5 seconds), possibly with other throttling going on. Cinebench 11.5 for instance ran about 1/4 as fast as normal.DanNeely - Monday, January 3, 2011 - link
Throttling down to maintain TDP at safe levels has been an intel feature since the P4 era. back in 2001(?) toms hardware demoed this dramatically by running quake on a P4 and removing the cooler entirely. Quake dropped into slideshow mode but remained stable and recovered as soon as the heatsink was set back on top.The p3 they tested did a hard crash. The athlon XP/MP chips reached several hundred degrees and self destructed (taking the mobos with them). Future AMD CPUs had thermal protection circuitry to avoid this fail mode as well.