2GB is the minimum to run Win 7 64bit so there is that...
This is a very strange thing to happen suddenly and it's probably good that you keep on top of your system's performance
Your temps as shown are fine so I'm going to go a different tack now and look at two things; First, it seems it may possibly be related to the Intel HD graphics driver you can download and reinstall the driver for your Intel graphics or, 2) try the steps shown here http/answers.microsoft.com/en-us/windows/forum/windows_7-system/laptop-keeps-freezing-and-making-a-buzzing-noise/de2c4317-5cfe-4258-87e8-835692824f3b
If that's not helpful, open the back and check that the CMOS battery is at 3v, replace if not (for some reason I cannot figure, that battery going bad can have strange effects on the PC's operation)
Ok, so I ran the SFC system scan and it returned with a message such as "this error was found but was unable to be fixed." But I have not yet tried to fix it manually, I wanted to try to update all drivers first.
Secondly for some reason the "Automatically Update" option for Windows Updates was turned off and there was about 400+MB of updates that needed to be completed. I set those last night and restarted my pc.
For some reason today I felt like switching the RAM cards again as a test. This time I insterted BOTH cards, large and small. The one slot which I said was previously not recognizing any cards is still not recognizing any cards, but I put the smaller 2GB card into that slot and switched the 4GB card in the place of the smaller card (in the slot the smaller card was previously that is actually recognizing it)
The pc managed to boot this time for some reason, but with the results I expected if it was to miraculously boot up. It only recognizes the larger card now, so both cards are installed but rather than 6GB I now have 4gb. Basically it seems like that slot alone is recognizing cards.
The pc has regained some of its former speed of course, now that it is twice the amount of RAM. Currently I am downloading and updating NVIDIA and Intel display drivers. I have not tested a video game for freezing and buzzing yet, I plan to do that after the updates are completed and do yet another full system scan for malicious software.
Although I should mention that for some reason my pc automatically restarted itself twice out of nowhere, whilst I was on the desktop. My temperatures are still fine so it is not a known overheating issue, as far as I can tell. I decided to go the the advanced section of system properties and disabled the "restart on system failure" option. It is to my understanding that disabling this will cancel a random restart during failure and possibly offer a blue screen with event log instead. But up to this moment (45 minutes later) the pc has not restarted or blue screened. I guess this is a good thing but I will wait it out and see if anything else randomly occurs.
So simply put, drivers are currently being downloaded and installed, security scan soon to be implemented, and then video gaming will be tested for freezing and buzzing. Why that one PCI slot has suddenly stopped recognizing RAM cards out of the blue is still a dilemma though.
OH also I must add, after the restart I now have a strange message on the lower right corner of my desktop saying
this copy of Windows is not genuine
This appeared out of nowhere out of the 2-3 years I have been using this laptop with genuine windows installed.
Ok so after all drivers updated, I tried loading a youtube video and the freezing/ buzzing still occurs.
CPU temperatures peaked at 70-72 degrees but for some reason my GPU showed no temperature. The software I am using shows my GPU to be the discrete NVIDIA card but unlike last time, no temperatures were shown. Could this be that the IntelHD graphics were in use instead of the NVIDIA graphics? and if so, why would the integrated graphics in particular be the cause of such an issue... I don't know, I will try to enter bios and try to manually switch to high performance graphics.
Ok so strange again. When viewing videos on a browser under integrated graphics there is slight lagging/buzzing but it is still there. When I switch to the high performance graphics, the freezing/buzzing is intensified, in fact I can say it is 2-3 times worse when I set this card to use.
The same goes for games, When I try to run them under IntelHD the freezing/buzzing is terrible. The problem is there even on a game's launcher rather than in the actual game itself. When I switch to NVIDIA card I expect better performance but nope, the freezing/buzzing again increases 2-3 times making the game itself or even its launcher almost unusable.
By the way, all drivers have been updated and yes the battery in the back is at 3V.