Performance test results: XPS 15: 90W vs. 130W adapter

Dell XPS 15 L502x
Intel Core i7-2760QM 2.40 GHz
NVIDIA GeForce GT 525M 1GB graphics card
8 GB RAM
Windows 7 Home Premium 64-bit, Service Pack 1
Performance testing software: PassMark PerformanceTest

I ran tests to see if there's any performance difference when running the XPS 15 on 90W adapter versus 130W adapter, and also versus battery. When using the 90W adapter a warning appears that the XPS 15 may run more slowly. I wished to confirm or refute that with some concrete evidence.

I used PerformanceTest's "Run Benchmark" command which runs a variety of tests on CPU, 2D graphics, 3D graphics, memory, HD, optical drive. I ran multiple tests under each power source.

Result summary:

1. No appreciable performance difference between using a 90W adapter versus 130W adapter.
2. Slightly lower overall performance score when running on battery power.

More detail:

CPU: score with 90W slightly lower than 130W, and battery a little further lower.
2D and 3D Graphics[/b]: about the same whether on 130W or 90W. On battery, they were somewhat lower.
Memory: score 30% lower when on 90W compared to 130W. Battery score slightly lower than 90W. The main differences were in Allocate Small Block and Large RAM, while other memory tests showed no appreciable difference.
HD and DVD: no difference.

Conclusion:

Overall score was very little different between 90W adapter and 130W adapter.
Memory test was the only test showing a large difference, about 30% lower score on 90W versus 130W.
So, it does seem true that a 90W adapter will cause the XPS's memory to score somewhat lower, but other tests are pretty much the same.
At this point Dell's on-screen warnings about the system running more slowly with a 90W adapter seem somewhat overblown.

Comments are welcome, and other comparitive testing is even more welcome. Please, anyone who has both adapters: run some tests.

 

Thanks for doing the testing. I assume the results were obtained with the Power Options->Power Plan set to "Balanced"?

I'm guessing that setting it to "High Performance" would result in the on-battery benchmark being the same as the 130W supply (at the expense of extremely short battery life). Just curious.

 

I'm just getting familiar with the laptop and with Windows 7, but as far as I can tell from Power Options and Advanded Power Settings, I think I have both AC and battery set to "High Performance".

 

Thanks for the info. I might be buying a 90w. if I do I'll post results.

 

Does it charge with 90W?

 

I'm sorry but passmark nowhere near pushes the system GPU/CPU at the same time. Try running 3dmark at full brightness on 90w then on 130w

 

Yes, it charges with the 90W.

DuranXL: nice negative post in response to someone who did the work of testing and documenting results. If you think you can do better, please do so and share your results instead of trashing others' work.

 

Constuctive critiscism is allowed.

My suggestion would be to run Orthos, Furmark and max out the speakers while running on full brightness. That should push the system to its very limits.

 

Absolutely! His tone was rather dismissive of the work I've done though, so it did not come across as constructive.

You want me to do tests with Orthos and other tests with Furmark? Do I just Google those, and will it be obvious which tools to install and how to run the tests? If not, more information would be welcome. I already tried two testing tools, including PassMark, so I don't want to have to spend a lot of time figuring out what to do. I'd welcome someone else sharing their test results.

 

Benchmarking programs don't necessarily give an accurate indication of max power draw. That's why furmark is used for overclocking, because it will push you system harder than anything you would encounter elsewhere.

Orthos would be interchangable with prime95, basically you just need something which will max out the CPU 100%. As for the speakers, I know mine are 8W, and from what I remember the new XPS series have even higher powered speakers, so it could quite reasonably make a difference.

Just run it all at once and that will get you about as close to your maximum power draw that's possible. If you just note the average FPS and time taken for a small FFT test over a minute or so (small time period to rule out thermal throttling), then you should be able to compare the two adapters. Both furmark and Prime95/Orthos are available for free simply by googling.

 

Sorry, you're confusing me. Now you've talked about a third one, prime95.

If you could, please pick one tool, the one you think will give the most meaningful result, and advise me specifically which tests to run and record.

 

Prime95 and Orthos are interchangable, they both achieve the same goal. They're both designed to max out the CPU. Furmark will max out your GPU. Run Furmark at the same time as either Prime95 or Orthos and you'll be maxing both your CPU and GPU at the same time. Just turn some music up high as well and that will be drawing the max power from the speakers.

In terms of measurements to take, run the tests for a minute or so and make note of the average FPS in furmark and the time taken to complete a cycle on Orthos or Prime95. If you're being restricted on the 90W power supply then you should get lower FPS and the cycles should take longer to complete.

 

Personal experiment. I got a new 9-cell battery that had 100% charge today. I plugged in 130W adapter (90W is used typical on my laptop, e6420) into my laptop while the battery was on. Dell has both 90W and 130W adapter with the same voltage and plug. I wanted to know what good is the control mechanism on the laptop is, and whether the advice that overcharging should not be a concern is true. Well, here is the result: My battery wore out by 1% for plugging in 130W for 1 second.
Then I re-calibrated the battery by draining the battery to 0% and I got my 100% back again.
I am now realizing that I posted on a wrong thread and that wear figures, as pointed by many people, are not accurate.

 

I doubt that. Those battery wear figures aren't accurate anyway, as we found in other threads.

 

I agree with you.

 

I've ben using the 90w adapter ever since I got my laptop. I have it plugged in with the 130W whenever I'm at home. I never thought of trying to test performance between the 2. When I take my laptop with me, I carry the 90W because I hate how fat the 130w is. You think the 65W will work?

EDIT: Tested it with a 65w adapter and it works to just power the machine without draining the battery, but it doesn't charge it. I didn't try playing any games or run some benchmark test, I only plugged it in and used it moderately, opening folders, web pages, word processing. I started about 3 hours ago at 86% charge and it is still at 86% charged. I am led to believe that it will only provide power to the laptop.

 

My L502x came with a 150W AC adapter. Is that out of the ordinary? It seems unnecessarily powerful for this laptop.

It has the HD-RGB LCD (I think, any way to confirm?), GT 540M, and 2630QM.

 

I have a Kill-A-Watt meter so I decided to do a quick test to see how much power I could get my L502x to use.

I ran Furmark, Intel Burn Test on maximum, while playing an mp3 in Winamp with the volume cranked up, keyboard backlight on, and with the screen on max brightness.

The most I saw the meter get to was 126 watts, but that was just a spike. It evened out to the 100-110 watt range after a few minutes.

I have the 130w adapter. Laptop specs are:
Intel i7 2720QM
Nvidia 525m
8gb Kingston 1866Mhz DDR3
SSD + hard drive in optical bay caddy
1080p screen

Possibly with a faster CPU and the Nvidia 540m it would be possible to exceed 130w constant power draw. I didn't realize they made a 150w adapter.

 

that they do I'm using the 150w adaptor now.

P.S. You onlu get the 150w adaptor if you have a higher end GPU, not CPU. So yeah, i think it's normal for a gt540m

 

I don't think that is correct because mine came with the 130w.

 

I've plug an 90W adapter in my XPS15 and I see some performance degradation when the battery is charging. When my battery reach 100% performance restore to a normal mode, but it could take up to 8h to charge the battery so I try to keep it always plugin so that my battery is always charged to 100% else I get probably 30-40% performance degradation.

When the laptop is charging, my SSD disk pass from 40mb/s to 1-2mb/s transfert rate then. I've replace it with a 130W power supply and everything is great since.

 

How to write a post - Sgraffite

I'm having no end of problems trying to use fullscreen exclusive mode xbmc on hdmi. I have gt540m, and 130w power supply. the battery is degraded, lasts ~10 mins.

So it's ok to use the 150w? Do you think this could solve my problems? (proposals to identify root cause welcome, arctic silver repaste completed, temps rarely soar imho)

many thanks

UPDATE:

I've just spoke to dell (and their sales affiliates). after much debate (re distance selling returns and rights) they took the part # for my power supply to my l502x- CN-0JU012-48661...

Immediately, the tone of the conversation changed, and Pete in sales @ 'upgrades.co.uk' reported I had a charger for a different laptop (a latitude).

Some more holding, and I got a quote for a 150w power supply - intended for use with l502x's etc.... £75

If it doesn't work, there may cost involved to return.

Does anyone have a 150w dell power supply?
(if so, can you please provide a part number?!)

if anyone can advise re (UK) vendor options... that'd be awesome.

thanks, Jonny