Radeon 3870 Component Question

I'm getting into hardmodding Radeon 3870s. I have 5 of them, 4 are in a rig for CrossfireX. One spare.

I will be upgrading capacitors that fit in the same place as the existing ones. I am:

Upgrading the 180uf 16V to 330uf 16V
Upgrading the 820uf 2.5V to 2200uf 2.5V (and filling in one empty one near the top of the board)
Installing the "missing" 6.5mm x 6.5mm SMT with 16V 220uf
Also installing trimmers for Vgpu and Vmem.

I'm curious about the four large square items on the board. They are labeled R47 738 M3K. I might want to replace these with something a little larger and more stable if it makes sense to do so. I have about 1.5mm to 2mm of clearance under my Koolance water blocks for these. What are these and what are the specs?

Thanks...

Those are inductors (coils), replace for higher inductance to get less ripple. I dont know the specs though.

Well on my test subject card, stock cooling, I have trimmers on it now and got it at 1.5V / 2.05V and 910/1210 speeds. It gets damn hot though, at idle it is at 1.2Vgpu and 300MHz and seems to be reasonable there. I haven't heard the fan kick into full speed yet though. This was a starting step for what I'm eventually going to do on my 4x 3870s in K9A2 Platinum water cooling. I'd like to get 4x running at 1000/1200 at a minimum. Then my Phenom 9600 at 2.75GHz can choke the system into posting a mediocre score. :>