S-XPS 1645 AC Power Throttle Issue Investigation

It just occured to me that my UPS has a little display on it that will show real time power draw. When i get home tonight I'm going to unplug everything from it and just have my laptop plugged in and I'll run some tests as well to see what the wattage draw is.

If the draw is a consistant 75 watts plus in most situations then it'd be a good assumption to think that the adapter does not have very much headroom for any little spikes in draw, which could cause stuttering in games at times and lower scores.

The way I see it (if it IS a power draw issue):

Game Scenario: You're in a hallway indoors in Left 4 Dead 2, you open a door leading outside thats full of zombies and a lot of things happen all at once:
-Zombies attack, AI processing via CPU
-textures loaded from RAM, maybe HDD
-GPU suddenly goes from rendering a very small area to rendering a very large area full of monsters, plus effects from gunfire, fire, explosions, etc.
-You're moving your view/camera around a bunch which is forcing all of the above to be loaded and unloaded and altered based on perspective

Any single item happening is going to cause at least one component to suck some extra power, and may not trigger the issue. The scenario above all of these things happen at once causing your GPU, CPU, RAM, HDD, and everything in between to suddenly say "MOAR!!!!" which could cause a temporary down-throttle that stutters the gameplay and sound.

Or maybe its really just a driver or power management feature causing the CPU to not work properly. We still have yet to get a real confirmation in the form of some one testing in North America with a larger-then-90watt adapter.

 

OK, one more 3DMark result and that is

AC adapter - Battery in laptop 62% at start, 63% at end - Max brightness - Wifi on
3D mark – 6882
SM 2.0 – 2465
SM 3.0 – 3026
CPU score – 2795

So slightly lower scores but not by much. I think there is still a good that it's the power supply and it's just that my machine has the wled, ssd and no bluetooth so is probably about the most power efficient 1645 you can buy off the shelf. Perhaps I also have a good power supply although slightly contradictary to that is my power meter has showed a maximum supply to the ac adapter of 86w in that last test although it's possibly a few watts higher on average than when the battery was charged.

Also my power meter is only a cheap £20 Maplins item so it could be that it is not that accurate.

 

Exactly 86 Watt maybe the maximum power provided by the power supply. Even though 3Dmark is not sucking the maximum power, the charger provide its maximum and hence will not be able to provide more power to the extra work.

 

This test was performed on Crysis alone.
Further tests, the one with the pictures was performed using Crysis and prime95

 

So neither Ollie nor Khlad (who both have the WLED) experience the 3DMark '06 issue.

Khaled, however, does have CPU throttling when running Crysis/Prime95 when on the adapter.

OCCT PSU test won't work on ATI GPUs: it requires CUDA, a nVidia feature.

Oh, BTW, I've run some additional tests and I don't think turning EIST actually lets you hit 13x. The C0 state (how hard the processor is actually running) is pretty low and CPU-Z confirms multipliers low as 5x when i7 Turbo.exe reads 13x constant.

 

Based upon 3dmark alone I don't seem to have the problems that some of you are encountering however Khaledseif makes a valid point about 3dmark not stressing everything out.

I don't have any games here (I'm not a gamer) that I can install but if someone can point me in the direction of a downloadable demo or something else that'll stress the GPU while something like prime95 stresses the cpu and which would give us useful results then I'll gladly do so.

 

I mentioned FurMark to stress the GPU....

 

If you're hitting 86watt with an SSD and a WLED then we have some solid evidence. Even if the RGB had the same draw, the SSD is going to draw considerably less then a HDD will when active.

Good reports man

 

@Ikjadoon: I dont think CPUz is showing the proper states on i7 yet, unless they've updated it recently.

@Ollie222: Crysis has a demo you can DL that does include the benchmark loop. Google ought to pull up the demo DL and the instructions to run it. (can't get a link as I'm at work and that stuff is blocked )

 

Also, UK (that run on 220V) power adapters tend to offer better efficiency in the AC->DC conversion by about 5-10%. You see it all the time on desktop PSUs, so I can think of no reason why the same isn't true here...possible the 90W part is either not delivering 90W for us, or it's delivering slight more than 90W for him.

 

Yes but bear in mind that figure is the amount of power used by the adapter and so the amount of power delivered to the laptop will be less than that due to losses in the conversion.

The 90w Dell state is for the output, not the input power which will be higher.

After doing loads of benchmarks I've just tried picking up the power adapter and it's absolutely roasting hot, literally at the point it would burn me if I held it in my hands.

Also while idling at the desktop my machine has just blue screened which is not good.

 

that probably would suggest that your taxing that powersupply pretty hard, even if its not making its maximum 90w output. agree? how cool is it in your room? temperature plays a portion in the role of max power a lot of times

 

Zlog, yup, you're right. I chatted a bit with the Real Temp developer and it was definitely running at 13x.

His hypothesis for the brightness issue is that maybe the system knows I'm trying to save energy by lowering the brightness, so it "disables" Turbo Boost when I lower the brightness

~Ibrahim~

 

Judging by the power supply feeling like it's going to burst into a fireball at any moment I'd say it's pretty much on the limit.

The room it was running in is about 20C.

 

thats pretty cool room, for being so hot. yikes

 

I'm just about to have a look at furmark however I'm going to struggle downloading the Crysis demo as it's 1.7gb but the connection I'm on at the moment isn't brilliant and it would take a while.

 

i'm running the 3dmark with the 130W adapter right now, ill run the 90W after that, and then teh battery.

the native res of my screen is only 1600x900, so i am unable to run the bench @ 1280x1024. won't matter as long as im comparing to myself, but to match your results to mine, youll have to run it at default settings, and 1600x900 res.

on another note, Purolator came today (Friday) with teh other end of my cord. they must have overnighted it, so im doing the tests with the proper connection.

im going to run 2 passes for each set, with a reboot between sets, i had one issue though. whenever i run prime95, its fine, but when i try to run crysis benchmark, it loads, and then crysis crashes.

 

max420:

Wow, you got that cord screaming fast... I've never seen Dell ship anything to Canada Overnight like that.

Wish they would do that for my laptop...

 

from the size of that power supply looks like its from the same manufacturer of the 360 brick.

 

Ikjadoon, if thats really how its designed im going to facepalm so hard i'll get a concussion!!

It makes no sense to tie in performance to monitor brightness at all. Monitor brightness should be totally independent of the performance. Especially with how bright the RGB is at full.

 

Ok, running Prime95 stressing out all 8 virtual threads so the cpu is 100% and then starting Furmark and running that for two minutes it runs at an average of 24fps both with the battery and also on the adapter.

With just Prime95 running it pulls 53W and then when I start Furmark it momentarialy pulls 110w before dropping back to a steady 92w.

As far as I can see there is no difference between using the battery or adapter although I'm not actually benchmarking anything with Prime95.

I'm about to crash out for the night now but if anyone has any other suggestions of anything to try then I'll have a go tomorrow morning.

 

Ive ran the 130W tests, I'm doing the first of battery still, ill post all the numbers when i'm done.

i was just concerned that because i couldn't get the other end to fit in snug, it may come loose, or be intermittent. i was surprised that the purolator guy even came, i bumped into him as i was heading out to 7/11

while i ran 3dmark 06 two times, the 130W power brick was slightly warm to the touch, the plastic was still mostly cool. a pleasant change from the 90W, which got quite hot.

INITIAL SCORES 3DMARK 06 default settings, 1600x900

130W 2nd run 6545

90W 1st run 6234
90W 2nd run 6282

battery 1rst run 6527 bat 100/86
battery 2nd run 6549 bat 86/75

seems like there is a diff, but very small........with crysis crashing if im running prime95, can anyone else suggest something i can run along side prime95 to load the gpu?

 

the 130watt scores dont look any better on the 130watt then they did on the 90watt scores that i've seen posted earlier but that can be a difference in system configuration... /anxious

 

i ran the bench at 1600x900

 

Try this. Should do the job

 

is your vid card and everything at max? i would expect around a 7000 score perhaps?

there is a little difference between 90w and 130w.. but i think its more important that the 130w matches the battery performances yes?

 

or verify if you're having the multiplier change when unplugging it from a 130w.

 

well to be honest, i was just running these numbers with the 130W for y'all, the important part to me, wasn't the batt and 130W scores matching, but the fact that i have been playing crysis, and CoD MW2 and i haven't experienced a framerate slowdown, or any sound crackling.

^^

edit: yes, i would expect a 7000 score, but may teh diff be the res im running the bench at? i have an external lcd here, 2048x1152 ill use HDMI to connect it, and ill run the bench at 1280x1024 with the 130W, see if i get a 7000 with that config.

 

oh yeah, i forgot it was different res.. anways yes your right. As far as it working correctly thats awesome!! and thanks!! and when the 90w is plugged back in problems come up again? I need a backup ps for my 1645 anyway the fact that it runs cooler is enough for me to ebay a 130 watt. will for sure go for the slimmer one lol

 

I'll be calling dell tech tonight. Sounds like that may have been the fix.

If you could do one last thing for us, Max:

Load up on the 90Watt play until you get stutter. When you start getting stutter. swap out for the 130watt and play for a bit to confirm that the stutter exists with the 90watt, and not with the 130 that'd be awesome.

The reason for swapping mid-game it to rule out any possible variables between tests.

<3 forever

Also, heres an easy way to make sure that different resolutions yielding different scores should be expected:

1024x768 = 786,432
1600x900 = 1,440,000

So the lower score you're getting makes sense

 

laptop is in boxing at the moment chuggin along through the system. After reading others experiences. im not risking calling or doing a thing til its physically in my hands.

I would encourage others as they resolve their problems to post, for proof to the dell reps. i figure a few more people after max420 resolving should pretty much be an open and shut case for them to send one hopefully.

I need a backup anyway, found the slim model for 24 bucks on ebay, not bad. fact that it runs cooler is a plus anyway, ive had one that ran hot on an old p4 hp it kinda suck.

and yes if ya could switch back and forth like zlog mentioned would be awesome

 

well here is something really interesting.

90W:



130W:

[/b]

Battery:



all in High Performance mode, with Prime95 running, and this app as well:

http://www.daionet.gr.jp/~masa/rthdribl/

 

X13 on the 130W..mmmmmm we might have a winner

 

coincidence that 90w brings 9x and 130w brings 13x?

max, you HAVE to call this in to a high-level tech. Even though they've probably already run some test like this at Dell Engineering. Let's make some noise.

 

THANKS, You proved our point. And thanks to anyone contributed.

 

what i find interesting, and the one thing im sure of, is that temperature is not the factor. it is the fastest, when it is the hottest. that temp had nothing to do with the multiplier, it was slowly getting hotter as the test went on.

 

So out of curiosity, if the PA-13 is the 130 brick, what's the model number on the slim version?

 

Just going to say this:

The i7-820QM's default multiplier is 13. So why is it going to 12x on the battery?

~Ibrahim~

P.S. But, still: CONGRATS! w00t!

 

Best news I've heard all night.

Thanks for that man!

 

i think that a lot of the pics dell uses are stock pics, xps support says there is only one 130W model, and one 210W model. until i actually see a pic of one, i don't think they exist.

 

So you believe there isn't actually a slim variant of the PA-13?

 

There's also a 150-watt model. That's marketed for the Alienware M15x, though it's compatible with the XPS 1645 if I'm not mistaken.

 

n3verm0re: that's correct, one of the slim cords i found on ebay had a slim pic, but under dell part number, i found a number thta matched one of the part numbers for the brick they sent me.

i would love to be wrong, and if someone has a slim adapter more than 90W, give me the part number. ^^

 

Ding ding ding i think we have a winner.

Also, I seem to stand utterly corrected. As promised, I was wrong about it being a software/power management bug.... and I'm totally blown away that Dell would not notice this as a possible issue. Something more to add to my complaint.

I'm going to call it in and get mine on order.

 

I've updated the first post with links to the new information and a statement for any newcomers letting them know that they need to take action.

Hows it look?

 

I ordered a powersupply off of ebay that had the slim picture. So ill see when i get it in. PA-4E i hope its one that works. ill let ya guys know when i get it.

zlog im glad ya stuck with your guns there. Its how things get figured out. i wouldnt say there isnt bugs in the power management stuff either as there was some oddness suggesting so in testing if i remember right.

Im just glad we have a solution for our high dollar laptops, yet oversight at dell is somewhat concerning. ill be getting my adapter replaced when i get my laptop in as well hopefully.

 

Looks good Zlog. I would like to thank all involved for finding a working solution. Hopefully Dell will start sending out the 130W adapters with new Studio XPS 1645 purchases.

 

this is my concern:

Dell Part Numbers: PA-4E, X408G, 330-1829, D232H, 330-1830

http://accessories.us.dell.com/sna/...s&l=en&s=dhs&cs=19&sku=330-1829&mfgpid=198276

and this is from the page, and the cord they sent me.

Manufacturer Part# : X408G | Dell Part# : 330-1829.

Dell part number 330-1829 is the PA-13 huge brick i have. that's why i think all these cords are the same big one.

 

Well we're starting the bullsht again, as 3 times in a row I've been hung up on while getting transferred to the "right department"

Wow, Just wow.

Is there a special number I call for the reps that dont hang up on me?

 

Ridiculous...

I'm too tired to call Dell and try to cut through their BS for a third time. When I get my call on Monday from the "Senior Support Representative", I'm showing him this thread and that's it. I'm done benching, done whining, done convincing. That pal better get me an adapter and soon.....lol.