A specific board number may be helpful since there are some variations of the board from what I could tell and it may affect the location of some components. I dug up a schematic for one of them (the board I used was an 820-2901, which *should* be this model or close to it). The board itself should be silk screened so you should be able to identify what components are what since they would actually be labelled.
Pad 2 (assuming it’s 2nd pad in from the left) on that connector does not go very many places. Really just to a test point near the connector and resistor R9050, which the schematic I have lists as “No Stuff” which means it is not populated on this particular board, or it wasn’t intended to be in this version of the schematic. Although it may be on the board you have. If it is, the side of the resistor closest to the graphics card slot is the one that rail is present on, on the other side it is R9050 is on the back of the board between the graphics card slot and the top edge of the board. If it is in fact no stuff, this line may just be unused since it would have no other way to connect to the rail on the other side of the resistor. In fact the schematic I have indicates this connection is broken because of the lack of resistors R9050 and R9051. So maybe you’ll be lucky and it won’t matter.
If there are resistors there, probably the test pad/via that’s right there would be the easiest place for that jumper, since the alternative is running a jumper to the other side of the board to the resistor. It’s the second test pad in from the left.