STH policy on using images for avatars?

[chilipepperz]

Is there a STH policy on using STH images for people's avatars on the forums? Same site OK?

 

[Patrick]

If you want to grab a system or CPU pic or something like that I am OK with it. No using the STH logo as your avatar though and prefer if you limited usage to STH forums only as an avatar.

 

[danielg4]

Please pardon the necro-hijack, but given that the thread title says "images" rather than "STH images" and that the answer to this doesn't appear to be stated anywhere:
What are the size limits? It has rejected my uploads both as too small (w.r.t. aspect ratio) and as too large.
Thanks