Power Supply Is 90% still a safe range for power used in a laptop AC adapter or is it too high?

CC Ricers

Shrink Ray Wielder
Original poster
Bronze Supporter
Nov 1, 2015
2,233
2,556
I currently have a thin mini ITX system running with a GTX 1050 working with a non-powered riser (seems like Gigabyte makes the power management run well on their boards). During gaming and benchmarks I get 80 to 85 W power used, measured at the wall. So this is after the efficiency loss converting from DC to AC.

Right now I am using a 150W AC power adapter from Dell but I want to downsize that. I found two ASUS power bricks that would look good with my setup. (the following links are just for reference, I can buy these bricks used elsewhere at lower prices)

This one at 120W: http://store.asus.com/us/item/201412AM300000015/ASUS+120W+Notebook+Power+Adapter

And this one at 90W: http://store.asus.com/us/item/201501AM080000048/A47375-ASUS-90W-Notebook-Power-Adapter

Both have a voltage compatible with my system. The 90W is about only half as big as the 120W one, but am I cutting it way too close if I go with the 90W adapter? What would be a safe minimum for my system?
 
  • Like
Reactions: 1461748123

1461748123

Master of Cramming
Nov 5, 2016
489
1,068
I currently have a thin mini ITX system running with a GTX 1050 working with a non-powered riser (seems like Gigabyte makes the power management run well on their boards). During gaming and benchmarks I get 80 to 85 W power used, measured at the wall. So this is after the efficiency loss converting from DC to AC.

Right now I am using a 150W AC power adapter from Dell but I want to downsize that. I found two ASUS power bricks that would look good with my setup. (the following links are just for reference, I can buy these bricks used elsewhere at lower prices)

This one at 120W: http://store.asus.com/us/item/201412AM300000015/ASUS+120W+Notebook+Power+Adapter

And this one at 90W: http://store.asus.com/us/item/201501AM080000048/A47375-ASUS-90W-Notebook-Power-Adapter

Both have a voltage compatible with my system. The 90W is about only half as big as the 120W one, but am I cutting it way too close if I go with the 90W adapter? What would be a safe minimum for my system?
90w should be fine. Power adapters have some headroom so realistically it should be able to handle ~95w-100w
 
  • Like
Reactions: CC Ricers

tinyitx

Shrink Ray Wielder
Jan 25, 2018
2,279
2,338
You really need to dig into the two specific bricks to check on their spec. One crucial spec is whether the 120W or 90W rating is a Max Output or Continuous Output. If it is the latter, then you might be OK. If it is the former, I would avoid the 90W, at the least. As your observed 80-85W is during gaming (ie a continuous demand), 90W Max is too close for comfort. A PSU can usually deliver its max output for a relative short period of time (ie not hours of gaming).

Eg the 90W in the 2 links below refers to its max rating.
https://www.ebay.ie/itm/NEW-Origina...arger-EXA1202YH-PA-1900-30-1305-/162049466849

https://www.ebay.com/p/Genuine-ASUS...Adapter-Power-Supply-19v-4-74a-90w/2255903918