Dell Precision 7540 and 7740 Owner's Thread

The 7740 works well with eGPU's. I tested a Sonnet Breakaway Box 550 with a RX Vega 56. You do have to swap an older pci.sys file in order for Windows 10 1903 v295 and newer to work with Radeon eGPU's. This might make NVIDIA a safer choice if its your work OS installation. There is some performance loss using the internal display vs. external display.

 

Just updated bios to the latest (1.6) and just like with 7530 CPU now runs 10c hotter and CPU benchmark performance seems around 10% worse. I suspect its the latest Intel vulnerability fixes which previously been known to have a performance cost when enabled. Since I dont massively care about Intel vulnerabilities as they cant be easily exploited without someone having gained access to your system first, I would like to roll back my bios, - but now whenever I run an older BIOS download exe my machine just freezes. Any ideas? I have bios downgrade enabled in my bios settings.

 

You can disable some of the mitigations via the registry, after the microcode update has been applied? Not sure about this one specifically.
https://support.microsoft.com/en-us...ive-execution-side-channel-vulnerabilities-in

 

I have a FIPS Fingerprint Reader but no NFC. Got missed out whilst speccing the laptop. Thinking of adding by purchasing new palmrest.

Anyone has an idea if the 7530 palmrest will fit the 7540 along with all accessory connectors like trackpad, smartcard reader and finger print reader?

 

Hi !

According to "Important Information" section description that you can find to the latest bios link here:
https://www.dell.com/support/home/u...de=wt64a&productcode=precision-15-7540-laptop

"Once the BIOS is upgraded, you cannot downgrade BIOS EXE/ Recovery (RCV) to the versions before 1.5.1."

So

1.3.3 26 Sep 2019
1.2.3 23 Aug 2019
1.1.3 08 Jul 2019
1.0.0 17 Jun 2019

are out of the game.

Would it be possible for you to check with latest throttlestop version "Turbo FIVR Control" section and post a screenshot like this (taken from here http://forum.notebookreview.com/threads/the-throttlestop-guide.531329/page-1091#post-10986562) ?



If you see "FIVR Control - Locked" like the one posted above, it means that 1.6 bios version has locked undervolt feature.

HP has already addressed this issue by releasing this latest bios update for zbook 17/15 G6/G5:
https://support.hp.com/us-en/driver...ile-workstation/22892902/swItemId/ob-242235-2

In "fixes" section you can see:
Enhancement to address security vulnerabilities CVE-2019-11157.

 

This has not been patched out of the Precision BIOSes: you can take a look at the earlier BIOS versions (1.5.1, in particular), and notice that the vulnerability has not been patched yet.

 

The thing is that he stated to have upgraded bios to version 1.6.0 and encountering problems while trying to downgrade as he was experiencing higher temps.

Like you correctly pointed me out, 1.5.1 does not report any CVE-2019-11157 reference under "Fixes & Enhancements" section.

But 1.6.0 bios link
https://www.dell.com/support/home/u...a&productcode=precision-15-7540-laptop&lwp=rt
under "Fixes & Enhancements" section only reports - Not Applicable. (at least this is what i see).

So no info by Dell about what type of fixes do this bios version has.

That's why i asked him to check with latest throttlestop version if he can see the "locked" status like reported on that picture. In that case, we can say that 1.6.0 bios version "kills" undervolt.

Edit: interesting note is that even 1.5.1 bios info reports the following:
Once the BIOS is upgraded, you cannot downgrade BIOS EXE/ Recovery (RCV) to the versions before 1.5.1.

So 1.5.1 is just some kind of delimiter: at 1.5.1 you can only have two options: stay at 1.5.1 or upgrade to 1.6 and eventually go back to 1.5.1.

 

Thanks guys, I have been able to downgrade to 1.5.1, but as suspected performance hit still remains the same as that was the update where CVE microcode updates were introduced (previously my bios was on 1.0). I've checked my registry settings for those vulnerabilities and it doesnt look like I have them enabled on windows side, so I guess the hit comes from microcode update alone. I will try to have a good moan at Dell support about it, to see what they can do to resolve as in some tasks performance hit is over 15% (probably in part due to increased temps), which to me equates to a fairly significant performance downgrade.
Throttlestop looks ok to me, undervolting still appears to be enabled:

 

Sorry to double post, but its not related to me previous post - just a bit of a warning to anyone wanting to mess around with Intel DPTF settings (i was doing it in hope of finding a cure for DPC latency fix, as someone reported it as a success by getting rid of DPTF drivers), do not do it - removing DPTF seems to introduce a pretty permanent 35W TDP limit on the CPU which I was not able to recover from by any obvious routes - system restore did not fix it, reinstalling DPTF drivers did not fix it, re-configuring DPTF settings did not fix it, Dell Power Manager could not fix it, only a full windows reset (effectively a re-install) brought it back to normal.

 

Tripple post, yay!
Dell support were very helpful and I've managed to downgrade back to 1.0 (needed to disable SMM Security Mitigation in BIOS before doing a downgrade). I tried 1.33 before it and whilst it improved performance when compared to 1.51 and 1.6, it was still not as good as on 1.0. I am now running 1.0 and benchmarks are very close to where they were before the bios upgrade, however temps are still higher then previously - TSBench 64M run hits 100c, whereas previously it maxed at 90c, so I wonder if updating BIOS leaves an imprint of new settings on the fan curve or voltages (curiously fan does not kick in during the short run of TSBench 64M, even at 100c). Might give DellFanCMD a go to see if I can improve on this.