Dell Latitude 5491 and 5591

Cooling can't be worse cooling than the 5491. Plenty of comments on the 14" model up-thread. Undervolt-stability should be essentially the same on all 8850s so you might also look at the 5530 thread, which has been busier. Undervolting has worked well for me, although it took that PLUS reducing the maximum turbo wattage slightly to get it to stop throttling entirely. It's still substantially faster than the 7820HQ 5520 or Macbook Pros we also have at work, at least on moderately multi-threaded stuff.

Has anyone gotten a 5591 on this thread? I'd assume like the 5491 it's cTDP-down at 35W, but it would be good to have confirmation.

 

AFAIK, the Precision 3530 is mostly the same laptop as the 15" version. As noted somewhere earlier in this thread, dual heatpipes, but still throttling.

 

Most recent BIOS update (1.4.3) lists lower fan sound levels when docked as an improvement. I don't notice the difference, but others may.

 

With latest 1.5.1 bios, the CPU throttling still happening without seeing rise in temperature over 75°C with TB16. It won't throttle straight away, but after around 5min running heavy program, and later back to normal for 1min then throttled again - repeatedly even the temperature has dropped to 50°C and the fan is still spinning like jet. Change power brick (240V) doesn't help. connect additional power directly to laptop doesn't help. Disconnect TB16 everything is back to normal.

This problem with TB16 is not noticeable if running the laptop under normal use. I run 2 instances of bluestacks only i found this problem.

 

Received an Aussie-spec i7-8850H Latitude 5591.

The good

1. The supplied AUO LCD is a "391-BDSB : Non-touch 15.6" FHD IPS EDP1.2 AG LCD (1920 x 1080), pn FD64N
LIQUID CRYSTAL DISPLAY, 15.6FHD, IN PLANE SWITCHING, AG, EDP1.2, AU OPTRONICS CORP"

Searching this prior to purchase gave me no info on panel gamut. Nor was Dell sales any use answering questions about it. Dell does list 72% gamut against their pricey, and very similar Precision 3530.

Upon receiving the unit Device Manager display properties tells me this is a AUO63ED, which google says is a 45% gamut LCD overclockable to 100Mhz or more. So good not good not sure.

https://www.reddit.com/r/Dell/comments/8lqqlp/dell_g7_auo_panel_overclocking/

This info is posted here so other researchers can get a Google hit about it.

2. The "socket 2" WWAN/M.2 slot (B+M) has a plastic surround. Moving the 2280 M.2 SATA SSD from the delivered 2280 NVME slot into this 2232 slot worked, sitting on an angle against the surround which would then prevent the base closing. It did appear the plastic surround could be cut to allow the 2280 M.2 SATA SSD to fit more horizontally so the base could fit over it.

If somebody else could confirm then could have a cheap M.2 SATA SSD storage option that allows simultaneous M.2 NVME slot use along with the larger battery. Using the 2.5" drive bay prevents NVME slot access & requires the smaller 68W battery.

Note: this slot cannot host a "socket 3" M.2 NVME drive.

As an aside, a deshelled Samsung 860 Evo SATA SSD will fit in the 2.5" drive bay alongside a populated NMVE slot.

The bad

1. The PCH chip has no heatsink or cooling on it. I had inconsistent Thunderbolt data transfer speeds likely due to PCH throttling > 80 degrees. WIth the base off, hwinfo64 reported the PCH hitting 88 degrees. My older Precision 7710 stays well under 60 degrees with consistent performance.

https://www.dell.com/community/Lati...th-ThunderBolt-dock-station-TB16/td-p/6184576

The plastic base can't be used as a bridged heatsink so would need a thermal pad bridge to the heatpipe to improve this. This is a factory design flaw.

2. short term TDP is 80W, so can get great CPU boost for up to 28secs. Long term TDP is an underwhelming 45W. By comparison, a XPS 9570 with a thinner chassis and more powerful dGPU sets long term TDP to 56W. Trying to increase this TDP using Throttlestop was pointless.. It ignores it and reverts to 45W. This appears to be 45W because Dell use the same BIOS for the 14" Latitude 5491 and so let the 15" use the same lower TDP.

As I need highest performance computing, the bad outweighed the good so it's being returned. Will look at getting a Precision 7530/5530 or XPS 9570.

 

While it's a gaming machine, a couple of my coworkers picked up Alienware 15R4 on sale from outlet last year, and if you want something with better ergonomics than the 7530/7730 and something with better cooling than the 5530/9570, it's worth seriously considering. If you need the highest performance possible, either one of those with an i9 or one of the Xeon 7x30s (or Lenovo Pxx, or a few other high-end gaming machines) are probably your best options.

The i7-8850H 5530s we have around here all see at least some throttling and I'd imagine the Xeon ones would be worse... not as bad as my 5491 though.

 

I have this laptop, have done some mods to it.

Single core cinebench top score 191 (normal priority)
multicore cinebench top score 1267 (realtime priority)

im currently at 4.4Ghz -195mv

PCH sitting around 40-42c

https://valid.x86.fr/pvra0r

Geekbench4
Dell Inc. Latitude 5491
Single-Core Score Multi-Core Score
5476 22296

 

Hey guys, quick question - does anyone know if the Latitude 5491 with a 8th Generation Intel® Core™ i7-8850H, which lists 'HDMI 2.0(Discrete)', can do 2160p @ 60fps with HDR to an external display? I'm specifically interested in the HDR component.

 

@Zero989, impressive results. Can you outline, or even better, show pics of your mods? As the base is plastic, can't sandwich a thermal pad on the PCH to dissipate heat.

 

Yeah I can show you, I've had to go back to 4GHz w/ HT as I'm using an eGPU now. PCH sits around 50-60c depending on eGPU load.

I beat that Cinebench score once I had faster memory. From 2400 to 2666. Obviously I did not keep it as the increase is so tiny.