A few days ago I acquired a Brand New Acer Aspire E 15 E5-571-74AP laptop, and found a frustrating problem.
Whenever the laptop is unplugged, the performance on games and other programs is stunning.
Whenever it is plugged in however, the clock speed of the processor drops down below 1 ghz as low as 0.60 ghz and performance is severely reduced. The clock speed drops only when a demanding program is open, and the program uses the same amount of cpu no matter the clock speed. It is definitely not an overheating issue. When I plug in USB devices the clock speed goes down. Again all this happens only when the laptop is plugged in to charge. Performance change is instant.
Intel Core i7-5500U 2.4ghz with Turbo Boost up to 3.0 GHz
Intel HD Graphics 5500 with up to 3839 MB Dynamic Video Memory
8GB 1600mhz DDR3 ram
1000 GB HDD
19V 2.1A AC/DC charger
I have tried changing the power options, making sure running on battery and while plugged in are exactly the same on high performance, I have tried removing event logs, I have tried removing all USB peripherals. It comes with bitdefender, an ebay app, amazon app, abMedia, Acer Recovery management, and Spotify. I tried disabling the start up programs and it did not help.