Unexplained temporary memory leak

Not sure how best to describe this problem other than a temporary memory leak that I can't determine the cause of. It's been happening for about the last 8 months or so, and happens maybe once a month. I'm running Windows 8.1 with all the latest updates installed.

Basically, over a period of 2-3 minutes my memory usage gradually increases up to 100% (I have 8GB). My computer becomes completely unresponsive for another 2-3 minutes and then suddenly the memory starts to gradually free up again and my computer becomes usable.

Because my computer becomes so unresponsive it's hard to monitor what is going on. After the computer starts to respond again I always ran process explorer to try to determine the culprit, but nothing stands out.

Also, there seems to be no pattern to when it happens. It has happened when I'm using LightRoom, it has happened when I was installing a game in steam, it has happened when I was just browsing in Firefox, etc.

I game a lot, but this has never happened (yet), when I've been in game. However, I do use Nvidia Shadowplay and I have read that this program can cause memory leaks (https://forums.geforce.com/default/topic/672846/nvstreamsvc-exe-memory-leak/#4116923). I followed the advice in this thread about disabling NVSTREAMSVC.EXE, but the memory leak happened again last night despite this.

Wish I could be more specific, but like I said my computer becomes very unresponsive when it happens, which makes it difficult to investigate.

Any advice on what might be the cause or what to do next time it happens in order to determine the cause? Could this be a hardware problem?

Try to use RAMMap to find the culprit.

CleanMem Free is good for memory leaks, but obviously it does not solve the cause, just the problem.

Could be a dodgy address range on a RAM stick, how many sticks do you have? If you have multiple ones have you tried taking one out and running with just one stick? It might help identify a troublesome stick.

Could be worth trying a memory test, Memtest x86 is one of the best for this sort of thing, here is a link