Wait, you're saying you can put an x1 riser into an x16 slot by just shorting the pins? I had no idea the x1 fit in the x16 slot..
You probably don't need to short any pins to use a 1x in a 16x slot. I use 1x risers for all my cards because that was what was in stock when I ordered them.
There is a long thread that I can't find right now discussing the short-or-not question when using risers.
Apparently, it's *generally* not needed. It depends on how the MB deals with PRSNT.
For some MBs, some need to do it for all slots. Some only for some slots.
In my case, I only need to do it for x16 slots. For some reason.