Bringing computer parts into Iran

Generally speaking, you won't have a problem, however it depends on which airport/border crossing you're entering the country from and how strict the individual officer dealing with you is. Most airports are fairly laid back and will be hassle-free. I would suggest you either attach the CPU and the memory onto the motherboard so that it looks as one unit, or maybe distribute them in different areas when packing, whichever that you think would attract the least attention (either to human eyes or to Xray machines!). If they do spot it, you just tell them that it's a present for your friend. worst-case scenario, they will charge you the import duty, but again, it is all hit and miss and you may not get into any problem at all. Also consider 1% possibility of things going differently than what I explained.

Tip: The nicer, cooler and more polite that you look, the less you'll run into problems with officials in general.

Resource: I'm from there and have traveled a handful number of times in and out.