Choosing computer hardware for repair and upgrades requires quite a bit of research and advice. iFixit sells parts for most Apple computers, and has an active community of repair experts on iFixit Answers who will be able to answer your questions.
SEARCH BEFORE YOU ASK
It's best to search before you ask on Answers. The same questions are often asked (and answered) repeatedly, so please spend a few minutes browsing for your device or specific problem before you post a question. Chances are good that somebody has asked something similar, and already received an answer. If not, post your question, but make sure to give as as much specific information as possible. The more pertinent information you provide with your question, the more likely the answers are to be fast, complete, and accurate.
For a full run-down on how iFixit Answers operates, check out the About page.