Residencies with multiple externs from multiple progams often see trends in GPA from the different schools. The classic example was a student rotating from a particular school a couple years ago who was ranked #17 in the class and had a 4.0. Obviously, at DMU, very few, if anyone, has a 4.0. So yes, most residencies are aware of these trends and take that into consideration. Having said that, at most programs, your externship performance will be more valuable than your CV so it's not really a huge deal either way.
Yep^^
At most programs, it basically goes in a systematic eval, and gpa isn't usually very high on most programs' list:
1) Did they pass boards first try? (the only common way of comparing all candidates on level ground)
2) Did they work hard on the clerkship? Motivated and good personality? Did they know a lot compared with peers? Did the residents like them?
3) Are they a very high ranked students or going to a school known to pass boards and produce good students/residents?
4) Are they top X% in their class? (not real important, but gains more weight at the schools that put out a "variety pack" of grads)
5) Research? EC? LORS? etc
Usually, if you have passed boards, you will get the clerkship unless your gpa is way below the program's typical standards for applicants. Unless ou are top quarter of your class, the clerkship might not be your top choice month at a popular program, but if you want to go there, make it work. From there, that clerkship's definitely your main way to make or break your luck with the program. It's basically a clean slate from there.
Gpa/rank is mainly important for "walk on" type candidates who try to interview into programs without clerking - and maybe even without ever setting foot in the hospital. If you give them no clerkship to go by, then most programs will barely consider you - unless your interview and paper app is better than most/all of their clerks. Gpa is also very important to those students who end up the scramble, but national boards is still far and away #1 for them.