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Old 2018-01-02, 03:43   #1
Dason
 
Jan 2018
Taiwan

1 Posts
Default Laptop occur black screen when run Prime95 on DC mode till because critical battery level

Hi Team,
Our QA team report an strange issue as below:
Laptop occur black screen when run Prime95 on DC mode till because critical battery level (OS default setting: 5%)

[Reproduce of step by step]
1. Boot to OS.
2. Unplug AC adapter.
3. Running Prime95 v29.4b5
4. Wait for laptop entry to critical battery level (OS default setting is 5% and critical battery action is entry Hibernate)
5. Find there are units will occur black screen.(Expect result: entry Hibernate)

OS: Win10 RS3 16299.125.

May I to know it is acceptable test method? As I know, user will let system entry sleep/ hibernate mode when running Prime95.

If it is not acceptable test method, please let me know, I will use this information to request QA team modify test method.
Thanks.
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Old 2018-01-02, 14:23   #2
VictordeHolland
 
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"Victor de Hollander"
Aug 2011
the Netherlands

23·3·72 Posts
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Sure, if you're trying to prove that Prime95 will drain the battery fast....

The reason the laptop is shutting down is to protect the battery, this is normal behaviour

Laptops usually don't have great cooling, so they'll throttle after a few minutes. If the air intakes/exhaust are clogged with dust it could overheat.
If it is shutting down before the battery is (almost) empty, it is probably overheating.
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Old 2018-01-03, 03:21   #3
LaurV
Romulan Interpreter
 
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Jun 2011
Thailand

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@OP:
Try the following test:
- charge the battery
- unplug the cord
- run p95 (let it run for few minutes, to be sure the LL/DC is fully running)
- take a stopwatch to measure the time (there is an app on your phone that can be used as a stopwatch)
- enter hibernate (by hand, using the mouse or the keyboard, click start, shutdown, hibernate, etc).
- count the time (repeat two three times to be sure, do a time average)

Then repeat the same test of entering the hibernate state, when the laptop is battery powered, but without P95 running. Just start the laptop, play a bit with it, then enter hibernate by hand. Count the time till full shutdown.

Do not wait for the battery to discharge to the "emergency" point. The battery has to be charged. The goal here is to measure the time the computer needs to go to hibernate, with and without P95 running.

If there is a significant time difference compared with the first case, than you may be onto something here... Otherwise it is just your battery which is just too old, or too depleted, or too under-sized for the "full" consumption of the laptop. It is "normal" for "cheap" laptops that the manufacturers use a battery which is ok for most of the activities your laptop is doing daily, like office work, programming, etc, but it is not powerful enough to drive the CPU at "full throttle".

This, combined with a lot of memory, and a slow hard disk, will give you exactly the symptoms you mention. Because the discharge curve of the battery is exponential, the voltage is getting faster and faster down, when the battery gets empty. When you enter hibernate, the computer shuts down, but not before saving the current memory status on the disk. Next time when you boot up, the status is restored (all your windows and programs, etc), and you can resume your work from the point you left it before entering hibernating. More exactly, a file called "hiberfil.sys" will be created on your hard disk, and this file has the size of your RAM memory, it is a copy of it. Next time when you start the computer, this file is read and copied to RAM (restoring your windows, programs, etc). If you have 8GB of RAM, then this file has 8GB. Now, with a slow HDD, writing 8GB on disk can take long time (many seconds) and your battery in a 5% state will not be able to support writing on disk for so long time, especially when P95 is running. Therefore, the file gets corrupted, you will write (then read) some rubbish into/from it, and that is your black screen. When you enter hibernation, the programs in your computer do not receive the "shut down" message, to close, because they will have to resume next time when you restart. So they are all running, sucking juice from the battery. And as somebody said before, P95 is not exactly "battery friendly". Not at all...

Last fiddled with by LaurV on 2018-01-03 at 03:23
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Old 2018-02-12, 11:00   #4
Jason
 
Feb 2018

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Hi Team,
I also found this problem in my side, but seems not related to battery capacity.
Try to setting the critical battery level to 80% then run P95 under DC mode, and the system also can't entry Hibernate.
May i know it's running the P95 tool cause the system can't entry hibernate after system trigger the critical battery event?
Also, May I to know it is acceptable test method? Please suggest it.
Test item: P95-Blend
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