533MHz is one of the common clock rates. The 10600 is not in MHz but some bytes per second over the bus connection.
Both Crucial and Kingston have memory selection tools to get the right sticks. They may offer faster parts than are required for a very simple reason. As production techniques improve the speed goes up. And since there is no reason to keep speeds low, and higher speed parts will work fine, the lower speed stock is consumed and may never be found again.
I have 2 laptops, Toshiba Satellite A505-S6005 purchased at Bestbuy and Acer Aspire 5740, purchased in India (When my Dell Studio died all of a sudden)
Satellite has 4GB of RAM and Aspire has 3GB of RAM. Both have only 2 slots. If I understood correctly, both the laptops have DDR3-8500F RAM (533MHz). Crucial website suggestion for upgrade RAM is 204-pin SODIMM, DDR3 PC3-10600 or DDR3 PC3-8500 modules.
I am totally confused. They don't seem like to be the same as the one already installed in the laptops. Most likely Crucial is correct with their suggestion but I just wanted a human expert to confirm and a recommendation on which module I should go with (i.e. PC3-8500 or PC3-10600).
Also any recommendation on brand? Newegg has good reviews for G-Skill, Crucial and Kingston but (G-Skill PC3-10600 is little cheaper, with a good review).
The Screenshots from Speccy for both of these laptops are at http://www.mediafire.com/?lq554w6avvg8v
Many thanks in advance.