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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:

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.

 

Replies (159)
2 Bronze

So, after having another call with the dell tech guy, he confirmed that they have had multiple reports of in fact much slower booting after the bios update as well as being stuck at the dell logo when booting. 

According to him dell is working on yet another bios update that should resolve that issue plus some other things. It will likely take at least another few weeks to be finished...

Edit: He also mentioned that reinstalling Windows in Legacy BIOS Mode would resolve the issue of being stuck at the cost of not having Fast Boot. 

It shouldn't be a problem if you have stock ssd in Intel RST mode. If you had this problem before, than it probably has nothing to do with the update itself. I have the same config and BIOS boot time has always been around 10 secs. On notebook review forum many users updated to 1.1.15 and only those who had non standard config (950 Pro SSD, stock SSD in AHCI etc) reported similiar problems

2 Bronze

Gadfu

So, after having another call with the dell tech guy, he confirmed that they have had multiple reports of in fact much slower booting after the bios update as well as being stuck at the dell logo when booting. 

According to him dell is working on yet another bios update that should resolve that issue plus some other things. It will likely take at least another few weeks to be finished...

Edit: He also mentioned that reinstalling Windows in Legacy BIOS Mode would resolve the issue of being stuck at the cost of not having Fast Boot. 

It shouldn't be a problem if you have stock ssd in Intel RST mode. If you had this problem before, than it probably has nothing to do with the update itself. I have the same config and BIOS boot time has always been around 10 secs. On notebook review forum many users updated to 1.1.15 and only those who had non standard config (950 Pro SSD, stock SSD in AHCI etc) reported similiar problems

I have the stock SSD installed and had switched to AHCI hoping to bypass the RAID Controllers integrity check and speed up booting. This only led to random Bluescreens so I reverted back to RAID.

Switching from RAID to AHCI didnt have an impact on boot times at all - as you said, about 10 seconds. Only after BIOS 1.1.15 it skyrocketed to about 30 seconds.

The support guy was very clear, that being stuck on the dell logo at booting is a known issue and they are working on a new BIOS to fix it. I didn't mean to imply it was caused by the recent BIOS update in the first place. Sorry for the misconception. 

2 Bronze

Did you switch to AHCI? Most likely most of your problems are related to that.

2 Bronze

No, as I said, i switched back to RAID, cause of all the problems and no gains.

2 Bronze

So after some tinkering I think I solved my boot time issues by resetting BIOS to BIOS Defaults (not Factory Defaults) and then moving the SSD to first place in boot sequence before Windows Boot Manager and re-enabling fast boot. Boot time is now back to 12ish seconds, which is the same time as on BIOS 1.1.07.

This still leaves me with capped CPU speed to 1.69GHz on Battery with BIOS 1.1.15.

Also when stressing the CPU, Windows logs show "the speed of processor 1 in group 0 is being limited by system firmware" for each logical core, no matter if booted on battery or pulling the plug afterwards. 

2 Bronze

So after some tinkering I think I solved my boot time issues by resetting BIOS to BIOS Defaults (not Factory Defaults) and then moving the SSD to first place in boot sequence before Windows Boot Manager and re-enabling fast boot. Boot time is now back to 12ish seconds, which is the same time as on BIOS 1.1.07.

This still leaves me with capped CPU speed to 1.69GHz on Battery with BIOS 1.1.15.

Also when stressing the CPU, Windows logs show "the speed of processor 1 in group 0 is being limited by system firmware" for each logical core, no matter if booted on battery or pulling the plug afterwards. 

Take a look at your power scheme configuration in config menu/system/energy settings. Select the Dell scheme, reset to default and try again.

I once selected the maximum saving scheme, which resulted in a slower performance.

2 Bronze

Thanks for the advice. I alread figured it out. Infact it was caused by the only Dell Application that I had installed: Dell Command | Power Manager. Regardless of the Power Profile I chose.

After removing Power Manager everything is fine. 

2 Bronze

Hi

I installed the latest bios release on 5th of Jan.

But there is a new issues.

I can not restart my laptop. Every time I restart it get stuck at dell logo and not going beyond that.

Then I press the power button until and everything goes off completely. If I press the power button again it restarts normally.

I it happens every time I restart it. 

Then I reverted back to previous bios version 1.0.7 and restart issue solved.

??????????????????????????????

2 Bronze

I would suggest that all owners of the XPS 15 9550 (regardless of H/W options) go to this thread and read all 67 pages (at this time).  It has a plethora of info regarding issues/fixes for this line.  Just a suggestion, mind you.

forum.notebookreview.com/.../dell-xps-15-skylake-9550-owners-lounge.783377

Dell XPS-15 9550

Dell Desktop Alienware Aurora R7

HP Desktp Envy 750-175se CTO

2 Bronze

This is <Admin Note: profanity deleted>.  I'm on BIOS .19 and my mulitplier doesn't go above 31 (3.10Ghz).  The CPU is rated at 3.5Ghz.  I sincerely regret spending money on this machine, <Admin Note: soliciting deleted>.

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