BSOD irql not less or equal, occuring from general usage of PC

[Thaesha]

Hello everyone, this is my first post here so sorry if I've gotten anything wrong.

In a nutshell, around 4/5 weeks ago I was getting a few BSoD's with a different name/error to the one in the title, however these seemed to sort themselves out as I haven't had any of those particular ones since.

Today however, my computer threw 3 BSoD's at me, all with the titled error. I had a look around some other posts with issues similar to mine and decided to update some drivers. During the first driver update (for GFX card), I got another BSoD.

My comp runs very smoothly almost all of the time, although recently I have noticed a slight decrease in speed, many forums are telling me this is to do with memory?

I'm not too technically savvy when it comes to computers, so I'll appreciate any help! Many thanks

TL;DR

- 3 BSoDs, 1st & 2nd whilst playing (different games), 3rd whilst browsing Internet.

 

[Thaesha]

UPDATE: I've installed a bunch of "important" and a few "optional" Windows Updates, and have gone a little easier on my machine today - no BSoDs. However, if anyone does have any idea as to why the initial BSoD(s) were occuring, I'd be so grateful if you could share so that this doesn't happen again!