There's a widespread confusion among Cisco customers as to what the difference really is between Cisco approved memory modules and their third party counterparts.
First of all, it should be clear to anyone interested in this subject Cisco Systems that simply does not manufacture any of its memory parts!
The memory parts customers get when they purchase Cisco equipment are manufactured by a Cisco approved OEM (Original Equipment Manufacturer). The OEM could be any company from Cisco's Approved Vendor List (AVL) which includes companies such as OKI Semiconductor, NEC Electronics, and Samsung among others. It should also be noted that since Cisco Systems no longer releases its AVL to the public, thus the companies mentioned above may or may not still be on the AVL. There will definitely be new companies added from time to time and companies removed as well.
Approved / OEM or "first party" Cisco memory refers to memory parts manufactured by companies on Cisco's AVL; these memory modules have been engineered specifically for use by Cisco Systems and undergo strict and comprehensive testing before being approved by Cisco for use with their routers and other products. These modules are guaranteed to have 100% compatibility with their corresponding Cisco equipments and are backed by a lifetime warranty.
Third party memory modules on the other hand are manufactured by companies not on Cisco's AVL and are not tested nor approved by Cisco Systems. The manufacturer does offer warranty and compatibility guarantee for these memory modules but Cisco does not. And although manufacturers of such memory modules claim to be fully compliant with Cisco's specifications, Cisco does hold the right to refuse service, under warranty, when the fault is deemed to be caused by the 3rd party memory modules; and even if this was only discovered later on then Cisco will bill the customer for the service.
And while 3rd party memory modules are cheaper and useful for certain groups such as students learning Cisco equipment about, they do pose a certain level of risk for any business considering using these modules. Think about any unnecessary downtime and how much that will cost your business. Approved memory modules have undergone stringent testing by Cisco Systems themselves for use with Cisco's own equipment, they do not affect the service warranty of the equipment they are used in and the memory modules themselves are covered by a lifetime warranty.
It is simply the smarter business choice for any company to opt for Cisco approved memory modules. Even though the initial cost might seem higher, but in the long run they are actually cheaper as there is extremely low probability, if any, of incompatibility or faults. Cisco memory Approved results in a lesser need to maintain and service these modules and the equipment they are used in; think total cost of ownership.