Cheap is not always best when it comes to technology. But make sure the ram is not ECC. Also the chips that are not of good quality don't step well. Never cut corners on the essentials. Even thought it may be 133 mhz those chips may not have been labeled properly or they are just bad. Check with the manufacturer to see if there are known issues with the ram. Boxes have been known to leave the factory with the wrong ram.
A teacher without peer, yet a student of great disicpline