No idea. Your description is vague and there are too many variables to the situation. To begin with, the graphic should be used VERY SPARINGLY.
Start off with the sliders (except the very lowest frequencies) "zeroed out". This is their center point, no cut or boost. Now pull down the lowest sliders (20Hz-100Hz) because that range is 99% garbage (rumble, hum, pop noises, etc), and will muddy-up the mix. You should "ring out" the "hot nodes" of feedback, by slowly raising the system gain and then pulling down the slider(s) that relate to the pitch of the feedback ring. You should not be pulling down the slider by more than -6dB. Keep away from boosting the bands, this usually aggravates the feedback issue. Boosting is for DJ's.
Mic and speaker choices and their placement onstage will have more to do with the success of the mix than all the gadgetry you can throw at it.
BTW, what is the source for your mix- an Aux Send, a line feed off of an existing mix,...?

moonbaby you are a wealth of knowledge and im so thankful for your repeated intrests. so what im doin right now is sending an aux signal into another seperate mixer. straight into the line in on ch12 or wherever.then i come out of sub L&R out into 4 yamaha 12 inch monitors.the mixer is a junky old yorkville audio pro 512. 500 watt mixer.250x2.the FOH board is a soundcraft spirit LX7.the reason i drag that unnecessary 12 channel yorkville around is because by using the mic pre after coming out of the aux send it seems to make it so much easier to get them up and running.plus the yorkville has a 10band graphic on board which is a little easier than a 31 to deal with.and then of course there is the channel eq.and i just feel a little safer having an extra mixer around.i have never had any trouble getting a good monitor sound quickly setting it up this way.power is borderline but usually sufficent. anyway if i was unclear about what i'll be attempting here it is. aux send out into 31 band graphic eq,intoQSC700 outputting to two 12"yamaha floor monitors.FYI the lead vocals get a beta 58 and all other are a regular 58.one other thing is ,when im raising the gain to ring the monitors, how high are you talkin? norml stage volume? louder? thanks so much bro.

Well, I do the "ringing out" as high a volume level as possible without clipping the power amp or causing my ears to bleed....then I'd back it down from there, if possible.
Now as far as the Yorkville is concerned, I be confused here. Are you taking an Aux mix (or a general submix) set up on the FOH board, feeding THAT into the mic input on the Yorkville? If that is the case, this is not good, because that mic input will not "like" a line level input hitting it.
Can you say "gross overload distortion"?
There must be another way to access the graphics/power amp section on that Yorkville. Look around on the patch panel of that sled. Yorkville is actually pretty good about provisions like that. There should be a line in at the "main section". Try to avoid the input channel in every way, especially the mic in. Even an Effects Return section will be better than that. Don't let the name fool you. It's just another line level input that's routed through the thing.
You did list a couple of different signal flows in your post, so that addressed the Yorkville one first. If the other is simply this:
Aux Out from FOH> 31-band>QSC>(2) Yammie wedges
I don't see an issue with this one. You have (2) channels of power at your disposal, and (1) 8-ohm wedge on each one will yield about 60% of the 4-Ohm rated output. This will also let you control the volume to each wedge independently of the other, whereas if you ran both wedges off (1) channel (and mute the other channel), you'd have a bit more power, but less control.