Nope. In fact I'd advise never touching the GPU voltage.
As I recall, my 560ti back in the day was stock clock 823 or 830 or w/e (DCII ASUS), and I clocked it to 998mhz.
Stock voltage was 1.068 I think, I raised to 1.1. Used to hit 84 degrees but it was very nearly the holy grail 1GHZ 560ti which was one of the best binned ones you could get.
My 980 doesn't support overvolting however, and it's a really crappy chip unfortunately, only hits 1450mhz but what you can do :P
Power limit is needed so it uses the boost clock more, tbh I just stuck the power limit on 120% and left it at that, it just means it CAN use it if it needs it, not it WILL use it and made no real difference to heat but meant it could clock higher more because it had more power headroom. I see no reason to not put it at like 120% unless you experience wierd temps and then just ignore it forever. In my 980 that's what I did and I noticed no difference in temp and it just made my GPU score higher because on the log files I could see sometimes it needed more than 100 and now it can... even on stock! Obviously there is no boost clock on AMD but regardless.
So yeah, 120% worked for me just try it and see if the temps are fine then get to overclocking. No voltage changes needed, that's really only for super power users anyway.
The stock clock of the 290 is 947 and yours is pre done at like 1040 or whatever but that just saves you time. Overclock by 20mhz at a time and each time run 3d Mark Fire Strike about 3 times in quick succession. If you want to be super sure of stability run another benchmark after like Heaven, then if it passes all that without any issue then add another 20mhz. 1090 is actually quite decent for a 290 because yours is already oced 100mhz over stock, but 1100 seems to be about where some collapse and have to go back.
Obviously you will know when it hits the limit, driver will crash, screen will freeze or artefacts can happen, it will make sure you know lol. Sometimes wierd things happen like everything turns purple lol, happened to me on this Strix. If you get a driver crash put the clocks back to the last stable oc and restart the pc just to reset everything and get ready to work out your exact crash point on your oc so you can get as much as possible.
As I said, I'd say around 1100 you will find this. Keep monitoring temps at all times, shouldn't make a huge difference but keep doing it anyway, MSI afterburner overlay is good for that.
Next is overclocking memory... does make a big difference as well, do 50 at first then keep going up in 20-30s until that crash or artefact or performance loss from error checking occurs (I believe that is the reason)
Basically sometimes memory is stable at a clock but it's low performance, always comapre the benchmarks after. This is because it's getting errors and having to correct itself I believe. If that happens clock it back, but normally it will have crashes before this.
Again, keep checking clock speeds etc, eventually you will reach the perfect highest oc on your card without overvolting.
Overvolting would be next, I can't give you much advice on how much or anything on that card, not big on AMD and I've only overvolted one card before plus all of them have different tolerances. 290 can apparently do 100mv? Do that on a 560ti and it will be instantly fried!
Good luck!