I had a bunch of problems with my system as well. My machine was freezing and shut down.It was not booting to my ssd.
What I found out is my wireless card made by dlink had compatibility issues with dell. Its causing some kind of Irq conflict or memory conflict. So, I changed my wireless card to Intel. The second issue, I experienced was during boot up ,the SSD wasn't booting properly even though I set the ssd to primary in the bios. I switched the physical primary sata cable to ssd and it resolved this issue.I also have issues with over heating and noisy fan. It is running at 44 to 50 C normally. Dell says its normal. but I switched my compound to arctic ice still same results. with no heat sink it just goes to 50 - 60 quick. I am thinking of getting a liquid cooler but this machine is old I don't even want to spend money on it. What is your suggestion on the cooler? I also plan to up the memory . Any suggestions?