I'm running a PC with a SSD and 16GB RAM. I recently moved the pagefile to the SSD (set to System Managed) since this appears to be a reasonable option with modern SSDs.

I had a system crash whilst experimenting with overclocking and initially couldn't work out why the page file increased to 16GB on my SSD.

I discovered the answer here: Windows 8 and Windows Server 2012: Automatic Memory Dump - Ask the Core Team - Site Home - TechNet Blogs

For the next 4 weeks after a crash, the system managed page file will have a minimum size at least the size of the amount of ram in the system - 16GB in my case.

I deleted the key HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\CrashControl\LastCrashTime and the page file is now back to its former System Managed size - 2432MB in my case.

I hope this tip helps anyone mystified by the same issue.