In the past, "burning in" meant running the device at max load and max power for a period, to be sure that it was OK to sell the device. You don't want your product to be DOA when the customer switches it on.
In the universe of overclocking, it's said by some that burning in
CPU's,
RAM or what have you by exceeding the factory recommended voltage values pushes the atoms of the circuits into a better alignment for higher performance. Most Electrical Engineers say that this is hokum. All the same, it seems to help many OCer's attain their goals.
Interesting, I didn't know that you can buy
RAM directly from Samsung. I've used SEC DIMMs in the past, and liked them a lot. "SEC" is--or was-- printed on the Mem chips when Samsung makes the chips and the PCB board that make up memory modules. "Samsung" on the chips indicates Samsung chips "on thirds," aka the board that mounts the chips is made by who knows.
It's said that the manufacturing quality of the boards is just as important as what chips are on them.