One monitor brighter than the other one?

It's impossible to match two screens from different monitor Manufacturers/Panel Technologies as far as colour goes.
The basics like brightness, contrast can be roughly matched by calibrating each one separately, but that's as far as you can get. e.g. Using either or both the procedures outlined in post #2.

You would need two identical monitors with identical panels/technologies to get any sort of colour match.

I'm having the same problem and I'm nearly certain it's a setting in Windows 10 somewhere that I cannot find or use. I have 2 external monitors and they are both significantly less bright than my main laptop screens. Screens plural because I have 2 separate laptops (one HP and one Dell) with 2 different graphics cards but both the same issue connected via VGA to said monitors. The VGA cable has been eliminated as the culprit as well.
I have gone through every setting in Win 10 I can find and there don't seem to be any more to try. I've updated the drivers for both monitors and the NVIDIA graphics card on this PC but the other has Intel graphics built in. I have even changed the display adapter to the generic Microsoft adapter but all that did was make the second monitor disappear as Win 10 could no longer detect it no matter what I tried.
Of course I've already tried the monitors' own brightness etc. levels and then using graphics card to control color levels to no avail. I'm stumped. The only thing I haven't tried is calibrating them but I'm almost certain that won't help either. That seems to be for fine tuning colors and such and this problem is much more pronounced than fine tuning.
It's almost as if the external monitors are running on battery brightness settings but I don't even have that as an option in my power profile settings.
My HP laptop was previously hooked up to an Asus external display a few years ago, by VGA, and it looked fantastic - even brighter and more vivid than the crappy HP screen which is very listless and dull in general. I used the old Asus monitor without issue with the HP's original Windows 7 and also after I upgraded it to Win 10. Makes me suspicious that a more recent Win 10 update is the cause but I have no idea. Both laptops are up to date and I think I'd find more people out there reporting similar issues but I've found next to none.
I feel like it's something fairly simple I'm overlooking. Any help will be greatly appreciated.

First PC:

HP Notebook 2000 363nr
i3 370m
8 gigs ram
Intel graphics built in
Windows 10 home

2nd PC:
HP Precision M4500
i7 620m
NVIDIA Quadro FX 1800
8 gigs ram
Windows 10 home

Monitors:

Asus X223W

Dell E2010Ht

As I said in the other post it is just not possible.
You must have near identical monitors with the same Display Panel to have any chance of matching colours. That means same technology, identical materials like the same LEDs in the backlight, and same colour filtering materials in the LCD.

Drivers and the Graphics hardware, Windows 10 have nothing to do with this.

You have 2 different Monitors with different Display Panels, they will never be the same 'colours' put side by side even with calibration.
They will also have different menus for various adjustments.

A simple test with full screen primary colours of Red, Green, and Blue will show up the differences.

Calibrating is not only about fine tuning colours at all, there are a lot more elements to it than that.

I used to test repair and build monitors way back when there were many different graphic card formats pre and after XGA.By eye its impossible to calibrate two monitors to have an identical Grey scale even if they are the same model(diferent manufacture No chance).it looks to me that you may have a faulty monitor.Just set them to a resonable level.Unless you can get your hands on an expensive grey scale setup detector which mointors each of the R G B levels.
Good Luck.

RingTailCoon said:

This is a REALLY old topic but for months now I reversed it to just one (good) monitor. The other one is gathering dust.

Then mark as solved.