Dell XPS 15 L521X: A Detailed First Look
by Jarred Walton on July 25, 2012 1:10 AM ESTDell XPS 15 Thermal and Throttling Investigations
Considering the CPU throttling that’s occurring with the current BIOS, we have several sets of data to examine. We logged clock speeds and temperatures on the CPU and GPU using HWiNFO64, and we’ll analyze the results here. Let’s start first with the system running “stock” with the A04 BIOS. Again, the current results likely do not represent exactly what we’ll see from future BIOS revisions, but I expect temperatures will be somewhere between the stock and ThrottleStop figures we’ll discuss in a moment. For the stress testing that we’re doing here, we loaded up Cinebench 11.5 rendering with three threads (looped), and we ran 3DMark06 at 1080p on the four gaming tests in a loop. There are slight gaps that occur each time one test ends and the next begins, so a short-term drop in clock speeds isn’t particularly noteworthy; it’s only when we see sustained lower clock speeds that we can clearly state that the system is throttling.
Starting with the clock speeds, it’s immediately obvious how far the CPU is throttling and how significant the problem is. With our stress test workload we’re able to hit the thermal limits (around 80C on the CPU) in just 30 seconds, at which point the CPU drops to 1.2GHz from 2.8GHz. While our graph only shows the first couple of minutes, the 1.2GHz clock remained in effect for over five hours of stress testing, with nary an upward spike until we halted the tests. Most of the time, we were able to run this workload without problems, but we did experience at least one crash. There’s also the question of what would happen under more extreme environmental conditions, as our testing was done in a 70-73F AC cooled environment. Here’s a look at the temperatures for the CPU cores and GPU at stock:
With our particular workload, we reach a maximum CPU temperature of 88C after 20 or so minutes, at which point the cyclical nature of our workload causes the CPU/GPU to fluctuate between 79C and 88C every six or seven minutes (the length of time for a complete 3DMark06 loop). The GPU reaches a maximum temperature of 85/86C after 40 minutes, and again temperatures fluctuate depending on the workload between 76C and 85C over the course of six or seven minutes. A more difficult workload (e.g. Furmark with OCCT) might present problems, but we’re looking at a more realistic scenario and at least the thermal throttling keeps the laptop from crashing.
Running stock is well and good for many, but can we push performance any higher by increasing the CPU clocks? That’s what we attempted to do, and we turned to ThrottleStop for this purpose. Having successfully run all of our gaming suite at 2.3GHz using ThrottleStop, that’s where I started the stress testing. I was a little surprised when the laptop shut down after just 7.5 minutes. Ouch! The CPU cores top out at 100C and the GPU hits 93C, with the laptop sustaining those temperatures for about 30 seconds before crashing (powering off with no warning). With that result in hand (and confirmed with a couple of retests), I stepped the CPU clock back to 2.1GHz. With 200MHz knocked off the CPU clocks, the stress test ran successfully for 20 minutes before once again crashing, and this time the CPU cores maxed out at 99C with the GPU again reaching 93C. The laptop managed to run for five minutes after the first instance of those temperatures, so we’re at least heading in the right direction.
Next up I tried 2.0GHz, thinking I was getting close to “stability”, and the XPS 15 ran for just over an hour before it crashed once again. Maximum CPU temperatures dropped to 98C and the GPU topped out at 92C, but we’re not quite there yet. Interestingly, 1.9GHz on the CPU didn’t do any better, with crashes occurring after 45 to 60 minutes three times before we gave up, and similar max temperatures. At 1.8GHz, we finally reached relative stability, with the XPS 15 handling our looped workload for over four hours. The maximum CPU temperature at 1.8GHz was 95C, and the first time it reached that temperature was just over an hour into the stress test, with the core temperature cycling between 89C and 94/95C every six or so minutes. The GPU maximum temperature was 89C, cycling between 84C and 89C. We put together charts of the CPU/GPU temperatures for our four test runs and you can see them in the following gallery.
As for the system itself, surface temperatures are significantly lower than the CPU and GPU core temperatures reported by HWiNFO, and the chassis never felt uncomfortably hot in our experience—the silicone coating on the bottom helps in this regard, though it may also be inhibiting the radiating of heat through the chassis and contributing to the higher temperatures.
Noise levels are relatively loud (I’d guess around 40dB—I don’t have my SPL meter with me right now), but given the throttling issues the fan should really be spinning faster to compensate—and apparently it can’t. Also note that the exhaust is located under the LCD hinge, which is potentially exacerbating the issue. If the airflow weren’t inhibited by the LCD/hinge, it’s possible the temperatures would drop 5C or more, which might be enough to avoid most of the throttling problems. At idle, noise isn’t a problem at all, with the XPS 15 typically coming in at or below the noise floor of our equipment (30dB). I’d personally rather have a laptop that gets louder but doesn’t overheat, throttle, or even worse crash than a laptop that runs quietly but experiences all of those problems. Of course, in an ideal world you could get both reasonably quiet as well as high performance, but doing so with a thin laptop chassis isn’t in the cards right now. We’ve seen the same issues with throttling (or at least lower clocks) on most of the Ultrabooks we’ve tested as well.
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yyrkoon - Friday, July 27, 2012 - link
"I think the Acer M3 looks might tempting value when looking at the graphs. It's got about 90% of the power for about 50% of the price"I think it would behoove you to do a bit of research on Acer products. By reading through user reviews from where ever you can find them. Most likely you will find many, many negative reviews. After that try talking to a few people you know personally who have owned Acer laptops.
Also if driver support is important for you. In the past Acer has been terrible in this department. Even if a well known part is included, you might find that upgrading your drivers might turn out to be a huge hassle, or even impossible.
If you're looking for a good deal though Dell, and many other companies have good deals a couple times a year. Usually found on deal sites like bensbargins.net. You have to pay attention for a while, and be fast though . . .
JNo - Saturday, July 28, 2012 - link
I got an Acer for my dad and it's doing just fine after 3 years and he takes it out to do research on once or twice a week. I know a lot of people joke about them and that Thinkpads and Macs are better built but plenty of people say that they're actually ok with their Acers (it would behoove you to read a bit wider too I think).People on anandtech and other tech sites are usually enthusiasts who often spend money on better kit but I can't afford to spend $100s on better build when Acer quality is 'good enough'. Either way it'll have to be upgraded in 5 years anyway. Mercedez and BMW have better build than Fords or Vauxhalls but I can't afford them either.
yyrkoon - Saturday, July 28, 2012 - link
Point being. You can pick up some incredibly great deals by not impulse buying. Without having to sacrifice too much.Just right now there is an HP with a core i5 processor (2.4Ghz ) 6 gb RAM, an AMD 7670, with a 750GB HDD for under $600 ($575) Which I am almost willing to bet will outperform the reviewed laptop as it sits.
You're right though. Personally I can not afford to buy just any old laptop either. For many reasons. Cost is only one small aspect. Also, I can not afford to spend x amount of money only to have the darned thing break, and have it replaced, or spend money set aside for other things on shipping. To get the system repaired.
With all that said. I too have found several Acer systems tempting. Then I remember what I have written in the paragraph above. Which is I do not have time / money to spend screwing around with something that should already be working as intended. My values here are obviously going to be different than yours. As I have certain things I will put up with, and some which I will not.
Some cal that "peace of mind" Which is why Mercedes, and BMW exists.
CeriseCogburn - Sunday, July 29, 2012 - link
Except that piece of mind often breaks down on the high end laptops as well.Lots of lemons there, too.
A better way to go about it is not get the latest thing until enough test bunnies have done so and beaten it approrpiately to have a good answer on what doesn't work and what breaks.
I have to agree with the other fellow, I've seen a lot of Acer laptops that do well (perfect nothing breaks)over a very long haul, even many Vista models. Their downside is bloatware, and sometimes the re-installation of the webcam on a flat Win install - which can be a real pain - but that also occurs on Asus and other high end laptops.
So the bottom line is, bragging rights.
yyrkoon - Tuesday, July 31, 2012 - link
Well, I own an Asus, and it cost me $400. Plays games all at acceptable speeds. and all that.Own a Toshiba too, which also cost me $400 brand new. Doesn't play a lot of recent titles well, but it has served it's purpose. It is also 5 years old, looks and operates as if brand new.
Neither of these gave me issues when it came time to upgrade, or retrograde. Period, Both companies have drivers for just about every reasonable solution out there. And then some.
Also, that Acer M3 as reviewed by this site, sells for $1800 . . . SO yeah screw that. I can pick up and Asus with much better hardware, and software support for half the cost.
CeriseCogburn - Sunday, July 29, 2012 - link
You see concerning this metal encased mac clone, they will put up with nearly anything and live with it.Instead one could get a thicker off brand or branded beast and have zero throttling issues and a much prettier screen, but you know, when they are going for the drooling braggart's right to squirt that they have an aluminum shell, anything goes.
Zak - Saturday, July 28, 2012 - link
That's a really good looking laptop. What happened? Did Dell finally hired someone with sense of aesthetics??? But yeah, that trackpad is likely to be a problem for many.CeriseCogburn - Sunday, July 29, 2012 - link
Looks like a plain jane piece of crap to me - and I can clearly see the mac clone rounded corners.It's all in the heads of the wannabe in crowd - sad, really sad.
robco - Tuesday, July 31, 2012 - link
I use a MBP and I'm a little disappointed to see Dell reaching for a near four-year old design, but not being able to nail the thermals. My machine gets warm, but hasn't ever overheated. But the biggest concern is that customization is limited - even more than Apple. When I click on the configs in the Dell site, I can customize the software, but that's about it.As for Apple not being innovative, you can say that about every other company in business today. They all stand on the shoulders of those who came before them. But as this demonstrates, how components are assembled and in what sort of enclosure does matter, especially in a laptop. Milling most of the structure out of a single piece of Al is pretty impressive. The fact that Apple can make laptops with fast CPUs and dedicated graphics that still manage to be under 1" thin and less than 6lbs is pretty good.
But one of the biggest criticisms of Apple has been the lack of options. It seems that Dell is moving toward selling fewer hardware configuration to keep costs down. Too bad, used to be one of their selling points.
yyrkoon - Wednesday, August 1, 2012 - link
No one can say that Apple does not assemble good parts into their MBP laptops. That is, if they expect to be taken seriously. Yes, their cases are superb too.However, for people like me, that is not where the problem lies with Apple. In short, proprietary hardware, using proprietary software. At too much cost.
IF Apple sold their hardware, and Operating system separately / standalone. Personally I would have far fewer issues with them as a company. Also, I do not like their business model for their other mobile products
Honestly, I have about as much problem with Apple as I do with Microsoft. Maybe slightly more. Thing is, with Windows. IF it stops working for me. I can switch to Linux, BSD, or whatever other Operating system I care to use. All my own choice. On top of all that, i get to choose my own hardware as well.
So yeah, for me and people like me. "It simply *does not* work". Of course, we actually know how to use a computer too . . .