Hi,
It is possible that The RAM developed a problem after some "Burn In", or break in time... And as neilpzz mentioned, it's connection may have been loosened when installing the SSD...
It is also possible that the SSD could trigger memory problems that did not appear with the HDD due to it's much faster speed..
There is really nothing special required in the way of settings for a SSD..
They are normally a simple replacement for a HDD... Just plug them in...
Some SSDs require the Bios be set to AHCI for them to function, but not all..
It is also possible that the SSD has a problem that is not appearing in the testing... The SSD has a controller chip\firmware that may have issues that would not necessarily show up in a performance test of it's actual memory..