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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:
forum.notebookreview.com/.../help-needed-from-new-xps-owners-report-serious-bios-bug-to-dell.783715
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.
AffinityConsult
5 Posts
1
November 13th, 2015 12:00
I can confirm this as well.
i7/512GB/16GB RAM/4k
Bios 1.0.0.7
AffinityConsult
5 Posts
1
November 13th, 2015 12:00
I can confirm this as well.
I've also tried the new Fast Ring Windows 10 build and it is still happening.
Config : i7/512GB/16GB RAM/4k
BIOS 1.0.0.7
boed
29 Posts
1
November 13th, 2015 21:00
I can confirm - same power issue with CPU
Bios 1.07
XPS 15 9550
m.2 256 GB HD
i7
smaller battery.
cdode03
27 Posts
0
November 14th, 2015 07:00
same issue here. I7/4k/512Gb
wpforte
3 Posts
0
November 15th, 2015 06:00
I have the exact same issue. Performance is fine when booted up with AC on, and steps down when on battery (as expected), but when the AC is plugged back in the cpu speed stays capped at around 1.66ghz.
i7/4K/16GB RAM/1TB SSD with latest BIOS and all updates installed.
Annihil
1 Message
0
November 15th, 2015 09:00
I can confirm this issue.
Config: i7/16GB/4K/1TBPCIe
OS: Windows 10 Home v1155 build 10586
BIOS version: 01.00.07 (v1.0.7)
How to reproduce the issue: when AC adapter plugged in, simply unplug then plug the AC Adapter again, you will notice that the CPU muliplier is now capped to x17 (1.66Ghz) and cannot go further (normally x34).
arjunprabhu
6 Posts
1
November 15th, 2015 09:00
Is Dell listening.? this is an expensive machine, and we don't want want a defective machine which runs at half the speed.
An update would be appreciated.
I am shocked to see the previous response from Dell that the Dell engineering team were unable to replicate this problem. Are they that incompetent ?
Burtandernie
38 Posts
0
November 15th, 2015 13:00
Has anyone had screen flcikering? I have not tested the cpu issue but do have crazy screen flickering Also did you buy from dell or somewhere else
boed
29 Posts
0
November 15th, 2015 13:00
Uninstall MS Hyper-V if you installed it and the flickering will go away.
Burtandernie
38 Posts
0
November 16th, 2015 00:00
I have windows home. No huper-v. Also how do i check for this cpu issue?
DELL-Colin Hu
Moderator
Moderator
•
351 Posts
0
November 16th, 2015 01:00
Hi,
We are looking into this issue.
I have sent a few of you friend requests as I'd like to get some more information on the issue.
If I haven't sent you a friend request you can PM me, but if you do please provide your service tag in the PM.
Thanks
DELL-Colin Hu
Moderator
Moderator
•
351 Posts
0
November 16th, 2015 01:00
We aren't using the released version of the XPS15 - it's a pre-release engineering version. This is one of the reasons we can't replicate the issue.
We are looking into fixing the problem. I'll be keeping everyone updated until it's resolved
Anonymous
5 Practitioner
5 Practitioner
•
274.2K Posts
0
November 16th, 2015 01:00
Hello, I will be postponing my laptop order untill this issue is solved. I feel it unappropriate for such a high price product. Looks like unfinished work as is.
unlabeled
8 Posts
1
November 16th, 2015 08:00
So far 100% of all XPS 15s that I have observed have had this behavior and every person who has tried this on the various Dell online forums has also found it to exist. Perhaps the engineering team should use a production machine to test this.
devans3928
5 Posts
0
November 16th, 2015 09:00
While I have the same issue described here (1.67 GHz max when switching from battery to power), I think I've found another throttling problem in a different scenario.
I've noticed that running in a "High Performance" state from battery doesn't allow the CPU to TurboBoost above 2.6 GHz. Also, the CPU clock doesn't consistently stay at 2.6 GHz...it dips down to multiplier 8, (~800 Mhz) and only reaches near 2.6 GHz when the CPU is under heavy load.
In a high-performance state I don't expect the CPU to down throttle below the rated frequency, even on battery, unless the CPU gets too hot (this one runs really cool). I also expect to be able to turboboost above the rated frequency. The downside is that I'll chew through my battery pretty quickly, but that is what I'm asking the system to do with my choice of power-state.
In the very least the down-clock seems like a problem since the battery can deliver adequate power to run the CPU at 2.6 GHz under load. I've been able to TurboBoost from battery on past Core i7 laptops. My 5+ year old laptop with a Core i7-620M could boost up to the max boost speed from battery - granted this dual-core CPU has a TDP of 35W vs the 45W quad-core core i7-6700HQ.
Configuration:
XPS 9550
Windows 10 Pro + latest Intel chipset and thermal management drivers
1.07 BIOS (11/02/2015)
Core i7-6700HQ
16 GB of RAM
512 GB PCI-E M.2 SSD