Dell XPS 15 L521X: A Detailed First Look
by Jarred Walton on July 25, 2012 1:10 AM ESTFirst Impressions: Skin Deep?
When I first laid hands (and eyes) on the new XPS 15, I was extremely impressed. It’s such a noticeable upgrade compared to previous XPS laptops in terms of build quality that I really can’t understate the fact. Dell’s in a bit of a Catch-22 here, of course, with a design that’s very similar to the MacBook Pro 15. On the one hand, if they do a 15” laptop that’s similar but not built as well (e.g. the XPS 15z from last year), they get complaints from people saying, “Apple can do it, so why can’t Dell?” Now they’ve basically silenced those naysayers and instead they’ll get others accusing them of copying Apple’s design. Does that really matter, though? I’d rather have something that looks and feels like a high quality laptop that borrows good design elements from other successful laptops than to get a unique laptop that looks and feels poor. Dell has also taken a few steps to differentiate their design from Apple’s MBP15, and as someone who has often wondered, “Why don’t other OEMs make machined aluminum laptop chassis?” it’s nice to see a laptop that really nails that element of the design.
As good as the XPS 15 looks, it also has plenty of performance potential. The XPS 15z made some compromises to keep thermals in check, and with Ivy Bridge and Kepler moving the CPU and GPU to smaller process nodes Dell is able to increase performance within the same power envelope. 1080p gaming is still going to be a bit too much with some titles, but if you’re really looking for a gaming laptop Dell already covers that market with their Alienware brand. The XPS is basically a stylish and well built brand that straddles the line between business offerings like the Latitude and Vostro laptops and gaming offerings like the Alienware and Inspiron SE models. (Yes, if you didn’t realize, the new Inspiron SE 15 and SE 17 both sport more powerful GPUs than the XPS 15—along with larger, bulkier chassis that don’t have the cachet of the XPS line.)
The problem is that good looks and performance potential can only take you so far, and when you really try to put the pedal to the metal with the XPS 15, the engine overheats and you end up taking an unscheduled pit stop. How big of a problem this is will depend on what you plan on doing with the laptop. I can certainly see gamers getting very frustrated with the current throttling issues, but I suspect the next official BIOS update will largely address those concerns. For general use—Internet surfing, office tasks, listening to music and watching movies, video encoding, etc.—the throttling problems will most likely never even show up. It’s only when you really push both the CPU and GPU that heat becomes a problem. So if you’re not a super demanding laptop user but you want a stylish and sturdy laptop that should last for half a decade—and you don’t want to deal with business class laptops, or OS X and Apple products—I can still readily recommend the XPS 15 as a good notebook that pleases me on many levels.
As good as the XPS 15 might be for mainstream/fashion conscious users, for power users or enthusiasts that really like to push their hardware to its limits I suspect that the XPS 15 will come up short. Even if Dell can create a BIOS that won’t throttle as badly as the current A04 release, I remain skeptical of their ability to have the XPS 15 run a heavy CPU+GPU load without dropping clock speeds on one or both chips. 1.8GHz was stable with my ThrottleStop testing, but that’s in an air conditioned testing environment, and I wasn’t using the most demanding workloads possible. If you run a pathological workload or “power virus” like OCCT or Furmark or similar, and if you require a laptop that can handle such applications without throttling CPU or GPU clocks, you’ll want to look elsewhere—and probably forget about laptops that are less than an inch thick. And on a related note, I should mention that I’ve seen at least some minor throttling with several other “thin but fast” laptops, so Dell’s not alone here; we’ll be making a concerted effort to check for throttling on all future laptop reviews.
For now, the throttling issues are a big enough concern for me that I’m holding off on a final verdict until we can see what the firmware updates bring. I know from past experience that laptops that seem to run a bit hot and/or loud when they’re new will only get worse as they start to age. If running any game on the XPS 15 today means 100% fan speed and juggling CPU/GPU clocks to keep thermals within an acceptable range, a year or two down the road you might be looking at a laptop that can’t really handle gaming at all. Maybe that matters to you and maybe it doesn’t, but if you don’t plan on doing anything that leverages the discrete GPU, why even have it there in the first place? Depending on what Haswell brings to the table, we might actually see dGPUs disappear outside of dedicated gaming laptops like the Alienware line—and I’m not sure that’s even a bad thing.
If we were judging the XPS 15 by appearances alone, it would easily walk out of here with an award. Depending on what Dell can do with the firmware over the next couple of weeks, we might still have a delayed prize to hand out. Unfortunately, out of the gate the XPS 15 stumbles and Dell will have to work to make up the difference. Until that happens, the XPS 15 is a beautifully crafted laptop with some personality quirks that could be hard to live with long term. Make sure you know what you’re getting into before committing to a relationship, or you could end up feeling burned.
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JarredWalton - Wednesday, July 25, 2012 - link
I'll look into this when working on the "final" review -- e.g. when the next A05 BIOS is officially released. For gaming in general, I don't think it will matter too much, as most don't tax all four cores. Still, stranger things have happened.yyrkoon - Wednesday, July 25, 2012 - link
Well the reason why I say this Jarred. Is because of how I understand these CPU's throttle. If they do operate the way understand it. These should be able to clock higher with only two cores being used fully. Then a lot of games only really need 1-2 cores. But not all.I myself have tried this on a game that I know is CPU dependent. It did not increase performance for the game, but it does help with heat. Well, performance wise, it did help because I was able to overclock the processor. Then remain inside the same heat envelope.
However, my system is based on an AMD A6-3400.
JarredWalton - Thursday, July 26, 2012 - link
So I did a quick test just now. Setting Batman: AC affinity to cores 0-3 (or cores 0 and 2) resulted in throttling within the first 60 seconds or so of running the Batman benchmark. So I turned to ThrottleStop again and decided to go for broke and set the multiplier for "Turbo" (maximum) and disabled CPU PROC HOT. I reached a temperatures of 100C on the first two cores after running the benchmark three times, and while the laptop didn't crash I wouldn't be comfortable running those temps.Next, I dropped the ThrottleStop multiplier to 26X and retested. Cores one and two still hit 98C after a few loops, and performance wasn't any better or worse (89-90 FPS for our "Value" 768p Medium settings). Then I tried ThrottleStop with the multiplier set to 23X but without any affinity setting. Performance went up slightly (91-92 FPS), and all four CPU cores topped out at around 91C, so overall performance was slightly up and temps were slightly down by just restricting the multiplier more rather than using CPU affinity.
Obviously, results for affinity will vary depending on game. Some games will benefit from additional cores (albeit slightly) and others really don't use more than two. If you're really hoping to control temperatures, though, setting a 23X multiplier as well as affinity should be a bit better than just TS alone.
yyrkoon - Friday, July 27, 2012 - link
Jarred, thanks for taking the time to look into it.It is a shame that what I was thinking did not pan out. It was a shot in the dark to begin with. Based on personal experiences of my own. So I think what that confirms in my mind anyhow is that Dell needs to work on a much better cooling design for this series of laptops. Maybe just putting in a higher RPM fan will work too. Like I think you had suggested.
Personally, I would not care if the case design were a bit thicker to allow for better cooling. Nor would I care if the laptop were a bit heavier too. But as I stated in another post, I am most likely not the norm in my laptop usage.
alfling - Wednesday, July 25, 2012 - link
1) Please don't start here another "Apple fanboys vs Apple haters" battle like in most other reviews :)2) To the reviewer: many people experienced significant drops in download speed (upload keeps constant) when being out of line of sight from the router, while with other laptops (also older ones) keeps being good. Could you please try to walk away from the router and check for us?
3) To the reviewer (again): I heard some people complaining that in white or very light screens (like Google homepage) they can clearly see the pixel grid of the display, but nothing official has come from Dell yet. Could you please tell us if you experience the same issue?
Thank you in advance!
JarredWalton - Wednesday, July 25, 2012 - link
WiFi connection speed over longer distances is a bit of a craps shoot, but I did read somewhere that Dell is working on tuning the WiFi performance as well. There are so many variables at play (just the type of router and the testing environment introduce all sorts of factors) that without doing a massive amount of work I couldn't say if the XPS 15 wireless is underperforming or not. I'll try to look into this a bit more for the final (next BIOS) review.Regarding the LCD, I don't see the grid when looking at static content, but as I noted in the review, moving windows around really shows some "fuzziness" on high contrast edges. I see similar behavior on most TN panels, and it's caused by the 6-bit to 8-bit dithering/interpolation AFAIK. Trying to capture this in a picture or video would unfortunately require a better camera/lens than I have. Anyway, the LCD is better than a lot of displays, but the ASUS N56VM/VZ 1080p panel is better IMO, and so is the old XPS L501x LCD (which had better colors and gamut as well). Will most people notice? Nope, but enthusiasts and screen connoisseurs might. The "dithering effect" doesn't bother me, but the bluish cast of the LCD is definitely noticeable.
alfling - Wednesday, July 25, 2012 - link
Thank you very much for your prompt replyrnmisrahi - Wednesday, November 14, 2012 - link
Indeed, there are many problems with the wireless card. Unless you're very near your router, the speed slows down to 2 mbps, while other older machines give me 30 mbps downstream, of course.Look at this Youtube: http://www.youtube.com/all_comments?v=x-KFW7_UxJM
dragosmp - Wednesday, July 25, 2012 - link
So what's the point of a quad core Core i7 and a discrete GPU if the chassis can't cool them? So you do have 4 cores than can potentially go to 2.8GHz, but if you try to actually use them they'll get throttled to 1.2GHz; or at 1.8GHz if this is as much as the chassis can take, and by the way thanks Jarred for doing this bit of investigative journalism. Unless they accelerate the fan further and/or modify the cooling/chassis, with all the BIOS engineers in the world they won't be able to pull more than ~1.8GHz.At this point I'm wondering, isn't the i7 a check box feature? From an engineering standpoint if the overall dissipation power of the chassis is xW you can take advantage of the thermal capacity and go over the xW for a certain period of time without passing the temperature threshold. Dell took this further: put a slim chassis with probably half the thermal capacitance of the old XPS 15, made it slimmer thus reduced the dissipation power and kept the same TDP CPU (which is itself surpassed while Turbo-ing). I wonder what if a 25W DC Core i5 would be faster than the 35W i7 in most apps, even heavy threaded apps, simply due to it keeping higher clocks per core.
As a engineer I see no point in this, but if I were a seller I sure wouldn't want to be the only one that doesn't support the fastest CPU as pointless as that may be.
JarredWalton - Wednesday, July 25, 2012 - link
I think the issue isn't the quad-core CPU so much as the total amount of power the cooling system needs to dissipate. If the GT 640M GDDR5 can use 40-45W of power (which seems about right) and the CPU uses up to 35W, then the cooling needs to be able to handle at least 75-80W of heat in order to avoid problems. Given what we're seeing with throttling, it looks like the cooling is probably only able to handle 60-65W, so something has to give.As far as the quad-core being useless, keep in mind that I never saw any throttling when running just CPU-intensive workloads. It's only the combination of CPU and GPU both being loaded where we run into issues. Games do that, and professional CAD/CAM type programs would do it as well, but a lot of other tasks aren't really going to be a problem I don't think. Even video editing probably doesn't put enough of a strain on the GPU to trigger throttling -- though I'll have to look into that later.