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Dell XPS 15 SSD NVMe slow after July 2016 firmware update and throttled CPU (Core i7)


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Dell XPS 15 SSD NVMe slow after July 2016 firmware update and throttled CPU (Core i7)

This question has been answered by paaland

Edit: 9/2: title change to reflect CPU throttling issues and discussion (second half of the thread)

I noticed a huge performance drag after updating the firmware and drivers of my XPS 15 9550. The update took place on August 4, 2016.

Performance of my usual apps (Chrome, development tools and IDE, etc.) went dramatically down. Typically, I would say things take about 3 times longer to happen. I checked CPU usage (normal) as well as memory consumption (also normal) to find out that the issue comes from the SSD drive.

On this laptop: 500Gb NVMe thnsn5512gpu7 NV (toshiba). Attached are the results of a benchmark run with AS SSD. All write speeds are abysmal, to say the least... that explains a lot, but I have no idea how to solve that issue, and whether or not it is really related to the latest firmware+drivers update shipped by Dell.

(Note: I checked the BIOS, it seems that the SSD is currently configured in RAID mode. Never touched that option before.)

Any idea? Other users impacted in a similar way. Thanks in advance.

Verified Answer
  • I managed to get the performance back by going into the disk properties and turning off windows write cache flushing. Both checkboxes should be checked. Write speed went to about 1400 Mb/s then.

All Replies
  • Do you mean the PCI Express Link State Power Management and Processor Power Management in the Windows Power Options panel? If so, yes, I used the High Performance plan and made sure the threshold are high and the the disabled the power savings for PCI express.

  • Paal: do you also have CPU speed issues with your Dell?

  • No. But I had very poor write speed with the thnsn5512gpu7 NVMe PCIe SSD which this thread was originally about before you started discussing CPU issues as well.

  • @Paal: I marked your earlier answer (disable cache) as the best one since it best answers the title of this thread.

    As for my original issue, it definitely is a combo SSD + CPU issue after the bios and/or Windows Anniversary update.

    The CPU issue is unresolved, although I could temporarily mitigate it by disabled the BD_PROCHOT setting using ThrottleStop. Nothing else I tried has worked. I hope Microsoft and/or Dell will fix that issue in the future. (A bit of googling will let whoever has that issue learn what BD_PROCHOT is linked to, and realize than quite a few users have struggled with that issue in the past.)

    Thanks all for your help.

  • I happen to have the EXACT same problem as nickfall with my Dell XPS 15. Poor SSD performance and CPU capped at 800 MHz. 

    My configuration is as follows: i7 6700HQ, 8GB RAM, NVMe THNSN5256GPU7 SSD. What I've tried:

    - install both old as newest BIOS driver
    - clean Windows 10 install --> problem persists
    - boot in safe mode --> problem persists
    - turning off windows write cache flushing --> problem persists

    Did anyone find a proper solution yet?

  • Ok, I had the same problem, but I think it's now fixed. I followed these recommendations:

    Disconnected the battery for 15 seconds and everything works like a charm. Strange though.

  • @Nyanes: I see - this is one thing I had not tried. Maybe one day, when I feel like opening that laptop again. I have ThrottleStop running in the background with BD_PROCHOT disabled, which does the trick. Thanks for taking the time to let others on the thread know :)

  • I've found this driver fixes the issue for me for now:

    (Previously had Windows write-cache buffer flushing turned off to fix it. Now I have the checkbox unticked and performance is still good.)