Anyone know why motherboards are mounted vertically in towers?

A random question that I couldn't answer with a quick google search.

What's the rhyme or reason to mounting it vertically. From a pressure load point, it'd be better to have it lay flat. Also cooling would work better.
 
Solution
Hi woltej1 ,
That used to be the case once upon a time , but not anymore these days there are quite a few cases where the motherboard lays flat
example - the coolermaster Haf xb , i think at the end of the day it is so that you can place all your components in a case without having the case extremely wide , most people dont want to take a a lot of room on their desk , going verticaly solves this issue.
Hi woltej1 ,
That used to be the case once upon a time , but not anymore these days there are quite a few cases where the motherboard lays flat
example - the coolermaster Haf xb , i think at the end of the day it is so that you can place all your components in a case without having the case extremely wide , most people dont want to take a a lot of room on their desk , going verticaly solves this issue.
 
Solution