Dell Precision 7540 and 7740 Owner's Thread

Thanks for the replies, including the cited one from @Soromeister. I didn't reply to this one because I didn't consider the repasting to be the primary suspect, but perhaps I need to rethink that.

The main reasons I have been reluctant to blame the liquid metal paste is that the cited post sounds (to me) as if the problem is that the LM could cause overheating, but I'm having the audio issues even when the CPU and GPU temps are very low and the system under light load. If three people really think the paste might be (or is likely to be) the problem, even if it's happening when things are cool, then I probably need to talk to HID Evolution and see what we can do about repasting with some other compound. Given COVID, I'd probably end up doing the repaste here, because I imagine HID is somewhat shutdown due to the isolation precautions, and I can't be without my work computer for weeks. I have Dell onsite support, but again...COVID, and they probably wouldn't do a repaste as part of that anyway.

I'm reluctant to undertake a repaste as a DIY, but if that's what I have to do, I will.

 

Great to know, Thank You!

 

I honestly have stayed away from liquid metal (makes me nervous) so I don't know how much of an issue this would be. Seems like an unintended direct conductive connection between the CPU and GPU wouldn't be a good idea, though, and it could cause unintended side-effects. I think that it would be OK to put liquid metal on the CPU only, and regular non-conductive paste on the GPU (since you're not going to be pushing that anywhere near the thermal limit anyway). However because the heatsink is one big unit, if you take it out you're going to have to clean and repaste both chips.

Repaste DIY is not bad at all (for non-conductive paste anyway). I've done it several times — it did make me nervous at first but I've come to understand that it's pretty hard to mess up. You can look on YouTube for videos comparing different application techniques (pea? cross? a little paste? a lot?) and in the end the difference in temperatures in the in result is no more than 1 or 2 °C (within margin of error). The quality of the specific paste that you choose to use matters more and you can find "benchmarks" for these as well. Dell has good disassembly instructions at support.dell.com so you just follow those to get the heatsink out and take your time.

You do need to clean everything well before applying new paste. Isopropyl alcohol works fine to get regular ceramic paste off. Not sure what it takes to clean off liquid metal. You'd have to be very careful not to accidentally spread it to anywhere it shouldn't be.

 

I doubt its the liquid metal, although personally I wouldn't have used it. Phobya Nanogrease would be a safer option, and should do much better than stock Dell paste.

I think the issue is likely there was a bad batch of system boards with an audio subsystem issue. Another user here had audio problems and had the system board replaced.

If you do have Dell onsite / mail in service repair you machine, be sure to completely remove the liquid metal and and any modifications done to it to contain it - you do not want to get your warranty invalidated or being sent a bill for a new system board, video board and heatsink due to the un-supported thermal paste. It may be a good idea to contact HID first and see what they suggest.

Were you able to try disabling the onboard audio in the bios and see if the issue still occurs?

 

Has anybody used this SSD enclosure on the 7740?
https://www.amazon.com/Thunderbolt-...refix=m.2+nvme+to+thun,electronics,227&sr=1-5

What transfer speeds does it achieve?

What is the best m.2 SSD enclosure to Thunderbolt 3 that achieves highest transfer speeds?

Thanks.

 

Does anyone have an issue with their wireless mouse pointer stuttering on a 7740? It's driving me mad. I've tried two different mice and different USB ports. It happens randomly, but possibly more often when I've just switched between programs. Never seems to stutter with the trackpad, so I think it's something to do with the mouse (driver maybe?) rather than the OS. It does it when the PC isn't under any load at all.

Thanks

 

USB I/O stuttering is not uncommon with these systems unfortunately. Disabling CPU C-states in the BIOS setup should fix it.

 

Thanks a lot.

Are there any downsides to disabling C states? If it's more power usage, I don't care about that as I run on mains power all the time.

 

It would be a very modest increase in power usage. (I didn't really notice any difference in battery runtime with it on or off.)

 

Does a USB wired mouse stutter? The trackpad in the Precision is on the I2C controller which is part of the PCH just like the USB controller. Wireless mice can also have issues if there much 2.4ghz EMI. I have a Logitech mouse using their lightspeed protocol that does not have as many issues with interference as their standard unifying receiver type or bluetooth mice for that matter.