Laptops General - Read Only

2 Bronze

BIOS BUG REPORT: XPS 15 9550, CPU Speed capped after switching from battery to AC power

I noticed a very similar bug for a Dell Latitude posted on this forum and am shocked that Dell has not fixed these bios bugs.

I have a brand new XPS 15 9550 and I noticed that when you connect AC power after being on battery power, the CPU frequency gets capped at 1.69 GHz as opposed to the usual 3.5 GHz. The only way to fix this is to then reboot or sleep/resume the system. What is the best way to report this BIOS bug to Dell? There has to be some way to get Dell to fix the issue in a BIOS update.

I have found several other users also complaining of this same issue:

I really hope Dell fixes this issue since it is unacceptable for Dell to sell such an expensive and premium machine with a glaring firmware bug that turns your i7 performance into a Pentium level of performance.


Replies (159)
2 Bronze

Well I've got until 1/7 to return this Dell XPS laptop to Microsoft and with no word or confirmation that a Bios update will definitely fix this, unless they release it and I can test before 1/7, it's going back. Disappointing to be honest.

2 Iron

I have until Jan 5 to return.  Will have to return to Best Buy if there's no BIOS fix before then.  This would be my second XPS 15 return to them.  (First return for space bar problem)  The last thing you want is this speed cap / prower problem to be a hardware problem.  If you are caught in a recall of tens of thousands of XPS machines that require mobo replacements, you are screwed.  Got to get out while the getting is still good.

It's also highly offensive that Dell is beta testing and in touch with reviewers/media, while leaving paid users in the dark.  Dell deserves massive returns.

2 Bronze

Guys, read the thread... They have fixed the problem, I'm running Bios 1.11.1 and I have no more cap issues. You just have to wait until they release it to the public. You'd be returning it for nothing.

2 Bronze

@electricalBear I take it you're a reviewer or Dell person which is why you have this newer Bios?  I've had one XPS with a drive problem and this 2nd unit has the Cap problem with no firm commitment by Dell that this is getting released anytime soon. I'm sorry but I'll take my $2K and consider buying again or go to a different mfg. What I don't want to do get stuck with this thing and have no recourse.  

It's bad enough I've got a Thunerbolt C post which currently is almost useless no easy way to connect Display port and the needed dock the TB15 is yet to be released which is needed for dual 4K at 60hz.   Basically I have paid to participate In a Dell Beta of their supposed "Flagship" laptop line for a machine that is almost as bad as the Microsoft Surface Book.

2 Bronze

I'm a regular consumer. After posting on this thread i was contacted by dell to live test a fix, which I did. I don't work for dell. I get your concerns, I was just letting you know that they have this problem fixed. Not sure why it's taking so long to release though... I've had the fix for weeks.

2 Bronze

Unfortunately Dell has done nothing to officially declare the issue "resolved".  One would think they would at least contact the reviewers/major tech sites and issue a brief update on the issues plaguing the XPS line.  They are headed down the same PR/support disaster path that HP and the others have opted to travel.

 While your model is fixed, my $2500 laptop is not.  My return window is rapidly closing...I can always look at this again in several months and see where it stands.

Dell XPS-15 9550

Dell Desktop Alienware Aurora R7

HP Desktp Envy 750-175se CTO

2 Bronze

Good to know and *** for the rest of us!  Well if not release my 2nd XPS will be going back and staying back for good.  Will have to decide to I bother with another Windows machine or just go back to Mac.  Too bad since I do like Windows but from the hardware side it seems to ***.

2 Bronze

I really hope this is fixed soon.

I already bought the XPS 15 9550 and its in production now.

I'm considering cancelling the order, although I know if I do it will be a customer service nightmare. The less you actually interact with Dell the better.

It's quite unfair that some individuals are given the fix, while the rest of the users are left to wait and wonder with no eta and no indication that it will be anytime soon. December is over now, and no updates on progress...

I wonder sometimes if Dell employees who deal with customers, are embarrassed or empathetic at all to the issues their users have. The way they communicate always seems so apathetic and cold... So different than Apple, who will bend over backwards for their apple care customers no matter what.

It's a different world from Apple, I'm wondering if I made a huge mistake buying a Dell...

2 Bronze

Seems that bios 01.01.15 is out.

I can confirm speedcapping issue is gone (i7, 4k, 1tb ssd, 16gb).

Processor SST is (still) not available.

TPM still disabled.


Haris163 did find out: I was just able to update the BIOS to 01.01.15 using the update driver software option from the device manager.

My reply:

Nice find, thanks for the update.

I noticed 4 firmware update:

1) system bios update (I think that was the text, since I started writing things down after I noticed their were 4 updates);

2) Intel ME firmware update;

3) Main TI PC 0

4) EC Bios

Anyone knows what 1..4 means??

Geekbench gives same results running on battery and AC, both ways peaks multicore at 3,3 Ghz and 3,5 Ghz singlecore.

View solution in original post

Community Accepted Solution
2 Bronze

@RaymondCDiijkstra  Thank you for posting this and a few comments.

Following the discussion on he thread I was able to open up device manager and do a check for updates on Firmware, and sure enough Windows 10 found something downloaded it and I was promoted to restart my XPS.

Upon restart my XPS hung with a black screen so I cringed a forcibly held down the power button to power off and then power the XPS back on.  Well 4 Firmware updates later I am back up and running and have confirmed both in Device Manager and Dell Support Assist that I am now on 01.01.15.

While it was doing this and seeing the file dates on the firmware update of 12/18/15, the only excuse I can think of as why Dell has not told anybody about this nor by the way is it even listed on Dells own support page is the holiday.   Seems like engineering got the fix completed as originally promised the holiday hit, and product marketing/web team is all off on vacation so the average consumer would have no idea of this fix.

Anyway thanks for posting this and to whoever originally found this queued update.

Top Contributor
Latest Solutions