Laptop not stable unplugged - even with stock settings

[4evrplan]

I bought a refurbished Latitude 5491 with an i5-8400h, and I've been learning to use ThrottleStop. I've had really good results with it plugged in, but unplugged, running TS Bench almost immediately causes the laptop to shut down. Prime 95 - shut down. I can't remember if I tried Furmark with it unplugged though. This is with completely stock settings. I tried setting MMIO to locked under TPL and under FIVR, I set the turbo ratio limits to 26 (stock is 42), and it still turns itself off when I run the benchmark. I'm not really sure where to go from here. Any advice?

 

[unclewebb]

Batteries in many laptops are designed for light internet use so you can check your email and maybe watch a video. Full load testing with Prime95, Furmark or the TS Bench can be overkill when not plugged in. If you are using ThrottleStop to prevent throttling, if the power demand is greater than what the battery can supply, your laptop has no other choice but to shut down.

refurbished

That might mean anything. Did someone clean off the screen and keyboard so it looks nice or was the battery replaced with a brand new Dell OEM battery? Many replacement batteries for laptops are junk.

Be happy that your Dell Latitude runs well when plugged in. Many of the Dell Latitude laptops with Intel 8th and 9th Gen CPUs have some horrible power limit throttling problems that cannot be easily solved.

 

[4evrplan]

Batteries in many laptops...

Okay. This laptop will be for my kid's school. I've already instructed them not to use it for anything demanding unless it's plugged in. I'm wondering if I should use some less intensive "benchmark" to dial in the TS settings while it's unplugged? Maybe I could just run pings in the background and refresh Gmail a few times? Would that be enough?

4evrplan said:
refurbished

That might mean anything.

Unfortunately, I don't know what all they did. I re-pasted it myself, and I know they didn't do that, because the existing paste was really dried up. But, at least the fan and fin stack were clean, so I'm pretty sure they at least did that. I was hoping they replaced the battery. On a full charge, it estimates over 12 hours of runtime, but I have not tested the actual runtime. While I had it open, I took the battery out and examined it to see if it had a manufacturing date. It did not.

Be happy that your Dell Latitude runs well when plugged in. Many of the Dell Latitude laptops with Intel 8th and 9th Gen CPUs have some horrible power limit throttling problems that cannot be easily solved.

I think mine actually is one of the models that historically had that issue. I don't know if I just got lucky or if Dell fixed it in BIOS or what. I flashed the latest BIOS firmware from August 18. 2024, but then I used these instructions from GitHub to unlock undervolting. I locked MMIO, and I was able to do -144mv on CPU and cache (I backed it off a hair to -139mv) and -200mv on Intel GPU and iGPU Unslice (backed off to -192mv because I was still seeing just the tiniest traces of graphical glitches in Furmark). I also changed the turbo ratio limits to 30, and it can run TS Bench and Furmark simultaneously for over 20 minutes without glitching or thermal throttling.

Thank you for your help and for this amazing tool that helps our computers run so much better!

 

[4evrplan]

I thought I'd try limiting the power draw when unplugged. It starts getting weird even before TS shows any issues. There is nothing in the Limits window and TS Bench doesn't show any errors, but the screen goes black for a moment or two. If I let the benchmark keep going, I might get EDP OTHER under limits, or it might just turn itself off completely, and then it won't turn back on until I plug it in. The temps are still low when this happens. There are consistently problems/weirdness if it goes over 15 watts, but I've seen the same problems at lower wattage too.

I'm attaching a log file from three runs of TS Bench. For all three runs, MMIO is locked, and turbo ratios are set to 25. This is as low as they go without being set to 0. I would have set all but one to 0 if that parked the core, but in previous tests, it didn't appear to do so, so I left them all on 25.

• In the first run, there was no other change to the settings. The power draw went up to 16.8 watts (line 589 in the log), and the screen wouldn't update for a couple seconds, so I stopped it.
• In the second test, I disabled turbo, and I got exactly the same results (line 786).
• For the third test, I checked "Clock Mod" and turned it down to 25%. The wattage stayed much lower that time, but the screen still went black momentarily before I stopped the test (somewhere between line 847 and 903).

 

[unclewebb]

I disabled turbo, and I got exactly the same results

The base frequency of a Core i5-8400H is 2.50 GHz. Setting all of the turbo ratios to 25 or disabling Intel Turbo Boost accomplishes the same thing. The CPU will run at the same speed either way.

Intel® Core™ i5-8400H Processor (8M Cache, up to 4.20 GHz) - Product Specifications | Intel

Intel® Core™ i5-8400H Processor (8M Cache, up to 4.20 GHz) quick reference with specifications, features, and technologies.

ark.intel.com

Clock Mod

I would not use Clock Modulation throttling. Adjusting the turbo ratios or the power limits are the preferred methods to throttle a CPU.

There are consistently problems/weirdness if it goes over 15 watts

Your CPU has a 45 Watt TDP rating. Your computer should not be doing anything weird when power consumption is only 15 Watts.

parked the core

All active cores of your Intel CPU are locked together to the exact same multiplier. You can have inactive cores spending some time in one of the low power C states. A core in C7 is disconnected from the internal clock so technically it is not running at any speed. When multiple cores are actively working on a task, they are all using the same multiplier. No need to over think things. Intel CPUs do a great job with power management without needing any user intervention.

I think we can conclude that your battery does not have what it takes to run your computer anywhere near its rated speed or rated power. That kind of sucks but the only thing you can do about it is buy a different battery. A replacement battery may or may not be any better than what you have. Buying eBay laptop batteries is like going to the casino. You might get lucky, or not.

 

[remixedcat]

for battery i recommend partspeople instead they are cheaper than going direct to dell in a lot of cases and are official dell oem batteries. do not chance knockoffs unless you want a spicy pillow.

 

[Kodehawa]

Either worn down battery or the stress software is drawing more than the battery was designed to take and the firmware didn't do a good job of throttling the laptop -- my bet is a worn down battery considering how old that CPU is by now (more than 3 to 4 years of use will wear down a battery a lot)

 

[4evrplan]

my bet is a worn down battery

The Latitude 5491 was released in Q2 2018. Would it even have any life left at all if it was the original battery? I guess I just assumed the seller/refurbisher replaced it but used something sketchy.

i recommend partspeople

Ordered. I'll follow up in '4-8 business days' to let you know how it goes.

 

[remixedcat]

The Latitude 5491 was released in Q2 2018. Would it even have any life left at all if it was the original battery? I guess I just assumed the seller/refurbisher replaced it but used something sketchy.


Ordered. I'll follow up in '4-8 business days' to let you know how it goes.

good luck

 

[Kodehawa]

The Latitude 5491 was released in Q2 2018. Would it even have any life left at all if it was the original battery? I guess I just assumed the seller/refurbisher replaced it but used something sketchy.

My 2016 lappy still has a Usable battery. It lasts like 1 to 2 hours and can't handle any kind of load, but it kinda works...

It kind of depends on luck a lot of times really. I've seen 90s laptops with working batteries.

 

[eidairaman1]

for battery i recommend partspeople instead they are cheaper than going direct to dell in a lot of cases and are official dell oem batteries. do not chance knockoffs unless you want a spicy pillow.

I bought a new brick from them for my dell xps gen 1 when the cord was damaged, this was many moons ago now

 

[4evrplan]

Ordered. I'll follow up in '4-8 business days' to let you know how it goes.

That fixed the instability. The old battery I took out of it is ZTHY brand, not Dell. The serial number has the four digits "2023" in it, so my best guess is that it was manufactured just last year, but it just doesn't work that well. Weirdly enough, the battery health tool in the BIOS reported it was in excellent health, and so did Dell's SupportAssist utility, but I definitely got crashes, screen cut-outs, and errors when stressing it with TS Bench and Furmark. The new Dell branded battery handled the same abuse with flying colors.

Now if I could only get the cooling system to magically work better, I could turn the turbo ratios up.

Thank you everyone for your advice.