Dear all,

My PC has been acting weirdly for a while now, and I'm desperate for some knowledgeable advice as I am running out of ideas! This might be the perfect place!

Problem 1
Problems started when I had some occasional BSOD's when playing certain "high-end" games (e.g. RS: Siege) after installing my brand new GTX1070. I did not have similar problems when I played those games with my HD5850 CF setup. Neither was I experiencing any issues when playing more "low-end" games (e.g. CS:GO).
Fix: Generally when experiencing BSOD's and ruling out software problems (i.e. after a clean install), I figure that faulty RAM is the likely suspect. Indeed: I fixed these problems by changing the RAM speed settings in the BIOS to DDR3-1066 (instead of 1333, which is the speed of my Corsair ram kit) as I discovered that my 3570k did not support the latter speed. I thought it was strange that these problems only emerged after my GPU upgrade, but it did the job.
Problem 2
a) Very occasional blue-screens during "ultra high-end" games (not RS:Siege, but .e.g. SW:BF), HOWEVER, I am not entirely sure whether this can be regarded as a part of this problem. This is why I did not post this in the BSOD section.

b) (main problem)
Frequent problems when booting up. Loading windows up until the sign-in menu always works fine, so I don't think these problems are HDD(SSD)-related. The problems arise when I sign in, and my computer takes +10 minutes to get past the "welcome" screen. Once I get to my desktop, it is nearly impossible to execute any programs. The explorer is there, but none of my other programs boot. If I get in a program (e.g. Chrome), problems persist because other "side processes" do not boot properly (e.g. many websites do not work because Flash does not load properly). Process manager does not show any high load on the system (CPU/HDD/RAM). This all gives me reason to doubt the health of my RAM once again. After multiple reboots (power PSU switch turned off), I manage to get into Windows and everything works perfectly fine (also more demanding tasks like gaming etc.).

What do you think of this? I ran a memtest over the night (so multiple tests) but no errors were found (although this does not entirely rule out the possibility of faulty RAM I assume). All my drivers should be up to date. I can post logs of my most recent BSOD's or of HijackThis if requested!

Thanks in advance!