Question Laptop runs faster when only using external monitor?

May 18, 2019
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I have a Thinkpad T570 (i5-7200u, 8G RAM, SSD, integrated graphics, with a 4k display). Since the day I purchased it, I found it to be a bit "throttled". Large spreadsheets would be laggy. Going fullscreen on YouTube takes 2-3 seconds. Weirdest thing was that when I use Netflix app or PotPlayer to watch videos, fullscreen would cause frameskip, but not maximized window!

My thought at the time was: "Hey, the new generation of laptops are like that. Too bad the industry is heading towards this direction. Next time I'll just get a non-ULV-processor laptop instead. "

However, this week I bought a 4k monitor. I connected my laptop to the monitor via a USB-C to DP cable. It runs at 4k resolution @ 60hz, same as the internal one. I disabled the internal display when using the external monitor. After using it for two days, I suddenly realized that now everything runs smoothly. There is no noticeable lag. It takes less than 1 second to go fullscreen on YouTube. Fullscreen video in apps no longer skip frames. Large spreadsheets can be viewed without scrolling lag.

And things just got weirder... I just ran a benchmark test using XTU. No setting was changed, but the score is now 70 points lower than before (with internal disp.). This doesn't make sense!

What is going on? How can the internal display cause throttling? Shouldn't it be the other way around?
 
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Is that a thing?
No.

I don't know why performance would be better with an external display. To be honest, I don't think you should have been having the performance issues you were seeing with the internal display to begin with. If your having non specific issues like that I'd probably do a clean install of Windows (not just a reset, but a complete new install), and install all the latest drivers. A clean install would get rid of all the bloatware that may have come with the laptop too.
 
May 18, 2019
4
0
10
No.

I don't know why performance would be better with an external display. To be honest, I don't think you should have been having the performance issues you were seeing with the internal display to begin with. If your having non specific issues like that I'd probably do a clean install of Windows (not just a reset, but a complete new install), and install all the latest drivers. A clean install would get rid of all the bloatware that may have come with the laptop too.
The performance issue had been there since the day I purchased it. I doubt a clean installation would do anything at all. I also doubt bloatware is the cause of the problem. If these were the cause, then switching monitor should have no impact at all.
 

Kamal007v

Reputable
Nov 15, 2014
54
9
4,545
My laptop games a lil bit better when connected to my tv. I close the lid while playing. Games that struggle to run in 720P runs alright in 1080P. It could be because we are shifting the load a lil bit to something else.
 

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