Intel’s Sandy Bridge i7-2820QM: Upheaval in the Mobile Landscape

Meet the Compal Sandy Bridge Notebook

Our review system comes from Compal via Intel, and as this is pre-release hardware there were a few minor bugs that have yet to be ironed out. For one, there was no way to disable the Bluetooth radio; perhaps a bit more alarming was that after resuming from hibernate, at least once the system fan decided to stop spinning. The latter problem made for some interesting hair-pulling, as suddenly benchmark performance started to plummet—particularly when running back-to-back CPU intensive tests! Early hardware anomalies aside, you can probably recognize the design elements from another major OEM, and it’s possible Acer/Gateway will ship something very similar to this system in the future; then again, it’s equally plausible that this was just a one-off design using existing parts so Intel could demonstrate their latest and greatest mobile platform.

Unlike the previous generation Clarksfield launch, Intel didn’t seed us with their absolute fastest mobile CPU this time around—probably because they don’t have to! We’re looking at the middle tier of quad-core performance this time, and while the i7-2920XM is technically faster, it’s hard to figure out who would be willing to part with an extra $500 just to get 100-200MHz more performance (and a 10W higher TDP). Perhaps the higher TDP will allow the Extreme version to hit maximum Turbo speeds more often, but it would likely hurt battery life in the process, so the 2820QM looks to be a good compromise. In fact, if you’re willing to give up another 100MHz and 2MB of L3 cache, the 2720QM should offer up 95% of the 2820QM performance for 2/3 the price. Here are the specs of our test system.

The basic features are par for the course; about the only missing “modern” feature we’d like to see is USB 3.0 support, but unfortunately that’s not part of the new 6-series Intel chipsets and it’s missing from this particular test system. Many laptop manufacturers will address that shortcoming with third-party chips, so we won’t worry too much about it for now. Intel did choose to equip their sample with some nice extras, though, like a 160GB Intel G2 SSD and a Blu-ray combo drive.

As a high performance notebook, the build quality is definitely lacking, but then only the CPU and storage options are truly high-end. There’s no discrete GPU, no keyboard backlighting, a run-of-the-mill (i.e. poor) HD+ LCD, mediocre speakers, a touchpad that didn’t have functional multi-touch (or even scroll/gesture) support at this time [cue Don’t Know What You Got Till It’s Gone], and a horrible dark glossy plastic chassis. We don’t actually have a price for the system as configured, since it’s not for sale, but we can add up a few of the components and make a guess that it will come in north of $1400+ ($1000 will cover the CPU, SSD, and BRD; $400-$500 should take care of the remaining items).

Again, this seems like more of a proof of concept rather than something most users would be interested in buying. Sure, when we get to the benchmarks you’ll see that the integrated graphics are certainly sufficient for “mainstream” use, but it’s hard to call a $500+ quad-core CPU and $400 SSD anything other than enthusiast/high performance. Pair this with a decent discrete GPU (i.e. from NVIDIA with their Optimus Technology), and it would be a lot more compelling. That’s what we hope to see when we start getting retail notebooks using Sandy Bridge in for testing, so we’ll leave off critiquing the Compal design now.

Besides the complaints, let’s address the other good elements before we get to the benchmarks. First, we like the 71Wh battery; it’s not an ultra-high capacity option like some of the 95Wh models, but it’s a good step up from 48Wh batteries. HDMI 1.4 also shows up, so 3D movie viewing is possible (with the appropriate display). The other thing to point out is the memory: DDR3-1600 in a notebook. In general applications, that probably doesn’t matter much, but when you’re sharing memory bandwidth with an IGP the added bandwidth that DDR3-1600 brings will definitely prove useful. Just think: system memory bandwidth now checks in at 25.6GB/s, which is equal to what you get from midrange discrete mobile GPUs (i.e. the 420M, 425M, and 435M). More importantly, most of the Arrandale laptops we’ve tested have used DDR3-1333 memory running at DDR3-1066, so we’re talking about a healthy 50% improvement in bandwidth (at least for the faster quad-core Sandy Bridge designs).

Now, if you’re looking just at the specs, the above may not seem like it’s going to set the world on fire. The TDP on the CPU is still 45W, which means it could burn through the 71Wh battery in under two hours quite easily. However, this is where Intel’s architectural changes start to come into play. Particularly at anything less than a heavy load, battery life is substantially better than you’d expect. In fact, this is the first notebook we’ve tested where you can get close to four hours of battery life watching a Blu-ray movie—no, not watching an H.264 file off the hard drive, but actually spinning your Blu-ray drive and reading a disc! Yes, a larger 95Wh battery paired with current-generation hardware would probably break three hours, but four hours from a quad-core system is amazing.

Battery life isn’t the only thing to impress; CPU performance on laptops just took a huge leap forward. Provided your system is running at moderate temperatures, the CPU will hit very high clock speeds for single-threaded and multi-threaded tasks. Here’s another area where the sample notebook might not be the best sample of what’s to come, as sustained loads would get the CPU to the point where it would have to back down from the 3GHz range, but we still measured performance higher than desktop i7-930 in quite a few benchmarks. And as for the graphics, Arrandale finally got Intel’s IGP to the point where it was competitive with AMD’s HD 4250 IGP; Intel’s HD Graphics 3000 generally more than doubles what Arrandale could manage, which easily pushes their IGP into the entry-level gaming category—and perhaps even further.

Improved battery life, substantially higher processor performance, and integrated graphics performance that can now hang with entry-level discrete GPUs makes for a holy trinity that will be difficult to match, let alone surpass. AMD will of course have their own Fusion products launching later this year, and we expect to see at better performance compared to Intel’s IGP, but when old Core 2 processors are already matching or exceeding AMD’s mobile parts, and Clarksfield and Arrandale were significantly ahead, Sandy Bridge ups the ante yet again.

Intel has shown data for several years indicating that laptops and notebooks are easily outselling desktops globally, but never have we seen such a big jump in notebook performance between generations. An old quad-core Kentsfield desktop could still outperform the fastest Clarksfield notebooks in CPU-intensive tasks, but now you’ll need at least a decent quad-core Bloomfield/Lynnfield to keep up with the i7-2820QM. Enough talk; turn the page and see just how fast notebooks have become.