I have configured my PC (A Dell Latitude D6420) per all of the recommendations I could find, but I am still having random freezes that seem to be HDD related (HDD light is almost completely solid). This has all started since I put my new 520 SSD into the system. I have used older models of Intel SSD drives in other laptops, and I have been generally very happy. This one... not so much. Any thoughts on what I might try? The system sometimes "comes back to life" after a few minutes, other times I have to hard-reboot it (after waiting 15-20 minutes with the system completely unresponsive).
Assumptions here you are using Windows 7.
Have a look in the Intel Toolbox software under SMART and see if it logs any issues in there.
Also are you using Intel's ACHI drivers? If yes uninstall them and revert back to the Microsoft default ones for Windows 7, there is no performance difference but I've often had problems with the Intel ones that never arise on the default MS Windows ones.
I remember now someone posted a similar issue to yours, and in their case in the SMART data for the drive the End-to-End Error count showed a problem, typically this should be zero, if not it shows data moving between the SSD and the motherboard is corrupt so it has to do lots of re-requests slowing things to a crawl. I think in their case a different SATA cable resolved the problem.
My Latitude E6420 have a similar issue,My computer is Latitude E6420,8G memory,HD is intel 520 SSD 240GB.
This driver working in windows 7 64bit.I try set SATA mode in AHCI and RAID,then the problem is same--random freezes.
When I used harddriver or Kingstong SSD NOW drivers(128GB) is no problem,only in use intel 520 SSD 240GB.
Basically has determined that the "only use the dell provided SSD can achieve SATA6Gb transfer rate, other non-dell provided SSD is default to work in SATA2 mode. Unless you use dell provided SSD otherwise the your SSD can't work in SATA6Gb transfer rate and work good. "shameless! Despicable!
I have the same issue with an Intel 520 120 GB SSD running 400i firmware. This is in a Lenovo W520 ThinkPad laptop. I have no SMART errors, but once or twice per week the HD light comes on solid and I can't do anything with the system. I have to hard reboot it. This is especially bad if I am logged in remotely over the weekend.
I found these posts about possible faulty sandy bridge chipset, showing these freezes: