For the most part, the heat spreaders are unnecessary. There are some situations (fanless liquid cooling boxes, builds which largely obstruct any air flow to the RAM) where they are helpful, but so long as you've got air circulating and aren't over-volting them, then there's no real benefit to them.
That said, I do remember seeing warnings from both Mushkin and Corsair that removing the heat spreaders was a dangerous task, as the ICs can be damaged by the force of pulling the spreaders off. At the same time, some people reported that the spreaders on some RAM were connected only by some weak thermal tape and in some cases, nothing at all.
So... I guess its up to you to see if you want to gamble.
As for the amounts of RAM, I currently have 8GB (and a Core2 Quad). Even running some huge games (Civ V seems to be particularly hungry), I don't fill up physical memory. Still, I'll be using 16GB on the new build because I plan on doing some development with multiple VMs and its nice to be able to give 4GB physical to a VM instance. The other applications for 16GB of RAM seem to be video editing, photo editing, professional graphics/rendering, and high-complexity CAD. Lots of those applications will run faster with lots of RAM. Of course... they'll only see a notable benefit if they are compiled as 64-bit applications. If not, some people with 16GB use large chunks of their physical memory as a RAM disk to further speed things up. However, in the age of SSDs RAM disks aren't as impressive as they used to be. They're faster, just not mind-blowingly so anymore.
That said, I do remember seeing warnings from both Mushkin and Corsair that removing the heat spreaders was a dangerous task, as the ICs can be damaged by the force of pulling the spreaders off. At the same time, some people reported that the spreaders on some RAM were connected only by some weak thermal tape and in some cases, nothing at all.
So... I guess its up to you to see if you want to gamble.
As for the amounts of RAM, I currently have 8GB (and a Core2 Quad). Even running some huge games (Civ V seems to be particularly hungry), I don't fill up physical memory. Still, I'll be using 16GB on the new build because I plan on doing some development with multiple VMs and its nice to be able to give 4GB physical to a VM instance. The other applications for 16GB of RAM seem to be video editing, photo editing, professional graphics/rendering, and high-complexity CAD. Lots of those applications will run faster with lots of RAM. Of course... they'll only see a notable benefit if they are compiled as 64-bit applications. If not, some people with 16GB use large chunks of their physical memory as a RAM disk to further speed things up. However, in the age of SSDs RAM disks aren't as impressive as they used to be. They're faster, just not mind-blowingly so anymore.