S-XPS 1645 Throttling Info. and Updates

Dell has released their solution to the throttling issue, if you have updated to the latest A07 or newer bios, and recieved a 130w adapter from dell. Need to call the reps and get a 130w sent free of charge.

After more testing looks as if the A07 bios has indeed greatly improve the performance of the laptop. More testing will continue to see where the limit is at, as there may be close to the throttling edge perhaps.

Purpose of this thread is to educate those about the throttling issues with dell's laptops. Specifically to the xps 16 with i7 processors. Also to show community driven solutions as we wait for dells response to this issue.

This is an advancement from the power investigation thread, to summarize the thread here is a quick list.

• The 1645 is supplied and designed for a 90w adapter which is undersized and cripples the laptop under gpu + cpu stresses, such as gaming and photo editing.
• Running on battery seems to let the laptop run more towards it potential.
• The problem severity varies and depends mostly on configuration and type of program being ran.
• A 130w or bigger power supply will not solve the issue alone, as the bios actively throttles to main 90w anyways.
• Through reps Dell seems aware of the issue. As of yet there has been no official announcement and is unclear if they will actually fully resolve the problem.

All the information in this thread is not by me alone, it comes from the 2000+ posts from many different users in the power investigation thread here. Thanks to those users is how we know so much today, and a special thanks to uncleweb for the only solution thats out now to get the performance that this laptop is supposed to have.

Verify you have a problem.
**Warning, when on battery do not stress both gpu and cpu using programs like furmark and prime95 at the same time. Not recommended, extra issues/failures have been tied to this.***
All 1645 currently are underpowered with the 90w and there is no official fix from dell to this date. As mentioned the degree of being effected seems to be very dependent on setups. To see whether the applications you are currently running are effected use as described here. Do note, if you dont currently game or run demanding applications now, it is unkown what the future holds and if problems down the line will pop up for you, as things become more multi-core and gpu aware.

Symptoms usually occur during gaming or other stressful applications. Can be in the form of extremely large stuttering under certain conditions. Even if these slow downs do not occur it is very likely you could see a performance boost by allowing the laptop to run properly, given a modern game. A quick test is to run on battery, giving the system a few min's to settle, and see if performance is improved.

The problem occurs due to the cpu slowing itself down to maintain the 90w power limitation set by the adapter. The cpu speed is calculated as 133mhz * a multiplier. This multiplier should be 15x + for most games, but due to throttling can be observed around 8-10x or the minimum 7x, a huge performance hit. If this is not enough then a second type of throttling is enabled and is discussed later in this thread.

To accurately monitor your throttling it is recommended to use throttlestops logging features. Sometimes is best to play in a windowed mode, and have throttlestop off the side of the screen to watch for throttling. To get the best results its recommended to enable logging as shown below.

​

To look for throttling VERIFY throttlestop is disabled and the checkboxes are unchecked like the picture. Throttlestop is also designed to stop throttling, with them checked it will not throttle, also if your using a 90w adapter with it enabled could run the risk of damage. Throttlstop Download

Under normal circumstances clock modulation and chipset modulation should show 100% for all 8 threads shown. multipliers should be well above 12x for 720qm and 13x for 820qm. If they fall below these limits under load of gaming you are being throttled as well. The majority of games use only 1 or 2 cores and should show a multiplier well over 15x.

To watch for throttling while gaming etc, click the log function on throttlestop and run the game/application. When done come back and open throttlestop log, and verify that there is no modulation and the multipliers are above 15x etc. If its not you are throttling.

Here is a video example by user Magt1000 showing there difference between running on battery and adapter. You can see the severe throttling causing choppiness vs battery being smooth. Video link HERE
EXAMPLE: Here are my results for tf2 and crysis, clearly showing throttling. Settings are not maxed, and resolution is 1024by768 so keep in mind this is not a full stress scenario, more just a casual run. The computer is also hosting and only looking at one section.

Crysis
fps throttled 43 fps, mult approx 9, no modulation (link to image)
fps unthrottled 64 fps, mult approx 14-15. percent increase 48% (link to image)


TF2
fps throttled 44fps, mult approx 9-10x, no modulation (link to image)
fps unthrottled 71, mult approx 14-15, percent increase 70% (link to image)

Its observed that lowering of the multipliers will reduce framerates significantly in games. If the multipliers are reduced to the lowest settings and the bios feels it needs to throttle more. It will activate modulation. Modulation is very severe and will cause extreme stutters and framerates tend to fall <10fps.



Current community devised solution to the problem. With much thanks to Uncle Webb
***DISCLAIMER USE OF A 90W ADAPTER IS NOT SAFE WITH THIS METHOD, AS THIS WILL ALLOW THE COMPUTER TO DRAW MORE THEN 90W, A 130W ADAPTER OR HIGHER IS RECOMMENDED. DELL ALSO HAS STATED THEY HAVE NOT TESTED A HIGHER RATED ADAPTER***

What is required.

• A 130w or higher ac adapter.
• Throttlestop program. by UncleWeb DOWNLOAD

Throttle stop is a program that does what it says, it disables dells throttling to allow the full performance of this laptop. By disabling the throttling the laptop then will be able to draw more then 90w, so a 130w or higher adapter is required. It has been measured through a kill-a-watt adapter these laptops need around 100-110 watts to run properly for current games. Performance increase can be double and allow hd gaming at 1080p resolutions.

The current throttlestop program v1.8 looks as so.

​

First read the disclaimer fully now to disable all of dells throttling do the following

• check disable clock modulation
• check disable chipset clock mod
• check set multiplier
• make sure set multiplier shows 13 (14 for 820qm)
• verify "ThrottleStop Is Enabled" message is displayed

Throttling is now disabled and laptop will be able to draw enough power for max performance. Extra features in the 1.8 version is listed below

• More data - increases sampling rate to give a better look at the multipliers and modulation. This allows better view of throttling
• Auto Turnoff - When switching to battery throttlestop will attempt to re-enable throttling. Some users have had problems switching to battery under high load. Possibly damaging the battery.
• Log file - Creates a log of multipliers and modulation, so programs can be run and performance later evaluated through logs.

Please donate to unclewebb if you find great success with this program. As he does this for free off his spare time, and his work is much appreciated as he continues to help us out developing more features into this program

*It cannot be stressed enough that this is at your own risk, and a 130w adapter or higher is needed to run safe at the moment.

**There is an issue when disabling dells throttling, not with throtlestop itself, but more of a side effect possibly with drivers. When keys are pressed in the game will cause servere FPS lag. To stop this, enable throttle stop and close the lid of the laptop to allow it to sleep. After a few seconds open the lid allowing the computer to wake up. Start your game and you should now be at maximum performance.

Throttling Explained
Its first important to understand how the intel i7 cpu's work. MHZ is calculated by taking the currently multiplier times 133mhz, ex 12x * 133 = 1.6ghz. The 720qm and 820qm run at a nominal 1.6ghz and 1.73ghz. To save power when the cpu is not under load, under normal conditions it will downclock to approximately 933mhz. Turboboost is the touted feature for these processors, If only one core out of the four is being used it allows the 720qm to clock up to 2.8ghz, and the 820qm up to 3.06ghz. If only 2 cores its somewhere in the middle and so on.

Throttling mostly occurs only when the gpu and cpu both are being loaded, by games and other demanding software. This is so the computer can maintain its 90w power requirement for the 90w adapter. It has been observed the cpu will first throttle the multipliers from the 15x-21x it should be during games, down to a measly 8-10x. (taking that max of 2.8-3ghz down to sub 1ghz.) The lowest multiplier it can go is 7x (930mhz) if that isnt enough to limit power consumption it will then do what is called clock modulation.

Clock modulation will kick in if the 7x multiplier is not enough to limit power alone. From what i understand, it basically is telling the cpu to ignore clock pulses from the clock, basically the cpu does nothing for some of the cycles and slows down processing immensely. This most likely is the type of throttling that coincides with user reports of slideshow type effects while gaming. Only way to monitor this is through realtemp and throttlestop as it shows the percentages.

There looks to be a third form of throttling that is used on the m15x that uncleweb is looking into. It is no known whether it effects xps 16 at all.


Dell's Update

Update 2/4/10
Bill_B from dell has finally come and answered some of the lingering questions. After 3 months of near no communications and conflicting reports, it would seem dell is finally coming out. Here are some of the more relevant posts to the issue.

Seems like dell now agree with us, and the adapter will be the proper fix. Looks as well like 90w adapter may be replaced with a higher wattage as well. ETA is still unclear at this point in time, but hopefully bill will stay in contact and know more after a few meetings time.





Extra related information.
1645 power related discussions. [0] , [1]
M15x response to throttling issues can be read here. link
Tinkerdude's report on dells throttling of latitudes (similiar mechanisms). link
See this post to revert back to an older bios (if it wont let you downgrade) Link


Any input/clarification is welcome. Its not my thread just a summary of the past thread, and all the info that may be buried in it. along with new stuff as well.
Updated 1-30-10

 

User submitted results (non-synthetic)

User ------ application ---fps --- fps with tstop --- powerdraw --- powerdraw w/ tstop --- screen ---processor
romills ------ Demigod --- 1-20 ---- 30-50 ----------- 65w --------- 115w peak -------------- rgbled -------- 720qm
A.H.A ------ burnout P - <10-15 --- 35-40 ------------ n/a --------- n/a --------------------- rgbled -------- 720qm
Siphen ----- D.A. max -- 10-20 ---- 15-30 ------------91w --------- 100 --------------------- rgbled -------- 820qm
Siphen ----- D.A. min -- 17-28 ---- 34-58 ------------91w --------- 100 --------------------- rgbled -------- 820qm
Siphen -borderlands min -- 8-22 ---- 34-62 ------------77w --------- 107 --------------------- rgbled -------- 820qm
Siphen -borderlands max -- 4-23 ---- 12-24 ------------95w --------- 105 --------------------- rgbled -------- 820qm
*post your results

Power consumption
100-110w for normal gamin on my wled + 720qm screen, peak 130 with furmark + prime 95, others with rgbled screens have reported up to 146watts with different configurations.

Siphens power numbers for max wattage per component, also agrees with testing done with my system as well. As you can see the laptop is very power hungry if it where to run at its max potential.

A test by mitchell2.4 that is more proof that a 90w is not enough, as it is pulling 93w from the adapter and the computer i severely throttled. LINK

This is power from the wall, not necessarily power to the computer, but as the 90w adapter just about catches a house on fire when it draws 90w from the wall. It wouldnt be safe in trying to get the actual 90w it should have.

Frequently Asked Questions

Q: Has this issue been resolved? When will it be?
A: The issue is not resolved. Despite what a rep may tell you if you order a 1645 today it will have throttling issues as described. Dell has not made any official announcements and any response to the problem may not be for a while.

Q: What other adapters will work?
A: The adapter should be rated 130w or above. While supplying 19.5v. Buying from dell is expensive and is suggested buying from other retailers.

Known adapters that work.
130w

• PA-4E slim 130w adapter
• PA-13 brick 130w adapter

150w

• PA-15 150w adapter

Fore more info on the 130w vs 150w, dimensions etc. Look HERE
*please send me model numbers that you are using with success

Q: The laptop seems to play my games just fine on the 90w.
A: As mentioned before, it is very dependant on the application and system configuration. Those with rgbled screens seem to have a lot more problems then those with wled. If the game is a recent game it is still very likely to see up to double the performance and smoothness with throttling disabled. May allow for full 1080p gaming for a lot of games.

Q: Mentioned other laptops have the same throttling?
A: It seems the i7's are a very power hungry processor and is likely the systems with i7's and 90w adapters are indeed throttling, although some core 2 duo laptops also have throttling issues but may not be power related. Though it is unclear how severe their issues may be with actuall performance, as this is mainly for the 1645. These are the systems that users have posted here recently stating similiar problems.

• Studio XPS 16 (1645)
• Studio XPS 17 with i7 processor
• Alienware M15x Investigation thread. LINK
• Latitude series (specific models anyone?)
• Studio xps 1640 (some signs needs additional testing for confirmation)
• Studio xps 1647 (recently confirmed via fear2)

updated 1/12/2010

 

Ahh, this was very much needed. I will add a link to this thread at the beginning of the investigation thread since the investigation is pretty much concluded at this time.

Thanks again for the great job you did at reconciling all the information.

EDIT: I think its important to emphasize that despite what Dell reps are telling people in various sales departments, THIS ISSUE HAS NOT BEEN FIXED. There is NOT a new motherboard. There is NOT a new power supply. There is NOT a new BIOS (Yet). If Dell tells you that this is not going to be a problem with your machine THEY ARE EITHER LIEING TO YOU, OR NOT INFORMED ON WHAT THE ISSUE IS (probably the former).

As of 12/27/2009, if you order a i7 1645 XPS, you WILL experience throttling on some/all of your applications without taking some additional steps to get your laptop performance to where it should be.

 

they totally know that they are doing this fellas lesson learned dont buy dell

 

will most definitely. Ill borrow your line and stick it on there for now. Give me a few days to get this up and going. I ran out of steam pretty quick tonight due to illness and my mind is just on cloud nine at the moment. I want to dedicate a section on the dell experiences/updates and will definitely mention what you say. As their methods/answers are a bit ridiculous.

I want to try to have anything worth knowing on this main page. mainly to allow everyone to discuss/post their experiences even if a bit offtopic. As nothing should get lost in a sea of posts.

 

This needs to be posted in the Dell Community Forums. Much larger audience there..

 

I actually just posted a link to this thread there. I wont hold my breath as it will be deleted in no time.

http://en.community.dell.com/forums/t/19312160.aspx

 

Wow, I hope they won't be so low and delete it

 

I'm almost positive they will. Thats why I even sorta called them out on it in my post.

 

thanks! great work!