The ProBook 640 G1 supports a faster memory clock speeds supported by processor than most laptops of a similar age and type to it. This portable PC supports a 1,600MHz processor memory clock speed, whereas most comparable spec notebook PCs that have been on the market for around the same time as it support a 133MHz processor memory clock speed. This laptop also supports 1 and 333MHz processor memory clock speeds.
This portable PC's memory clock speeds supported by processor (1,600MHz) is in fact the best supported memory clock speeds supported by processor amongst all portable PCs that have been around for a similar time to the ProBook 640 G1.
A 133MHz processor memory clock speed is the worst supported memory clock speeds supported by processor across similar types of portable PC.