well from what i can gather online FX-6300 should have about the same limits as FX-6350 since it's prettymuch the same cpu,
and actually people often end up running similar clocks with lower voltage on the 6300 which is quite surprising... my cpu comes at around 1.41 volts stock... as far as longevity goes - noone can guarantee anything but the "general consensus" is that you'll be safe until 1.5volts or even 1.55 as long as you keep the temperatures in check.. but i personally try not to go that high... and you shouldnt need to on a 6300
you only need as much voltage as required to keep the cpu stable and nothing more...
the LLC (load line calibration) setting is what dumps more voltage in your cpu under load
because "Vdroop" happens and voltage drops on all cpu's as soon as they get a good load -
this setting fights that and gives it more to keep it stable...so you find the right voltage by experimenting and doing stresstests
prime95 is very good for these cpus because it will be the first to show a core/cores fail... intel burn test can be pretty torturous on intel cpu's but it doesn't appear to work as well on amd - prime95 is always the first to go on my machine,
i wouldn't worry about 4.5 ghz to be fair... mine turbo's to 4.2 stock... and most if not all of them overclock extra 500mhz on stock voltage (mine included) there are slightly cheaper gigabyte models from same 970 series but the UD3/UD3P has 8+2 power phases which you ideally want for stable overclocking and longer motherboard's life (less strain/heat on the power circuitry and more precise voltage delivery)
here's some reading material that should sort out all of your quetions:
http://www.overclock.net/a/about-vrms-mosfets-motherboard-safety-with-high-tdp-processors
http://www.overclock.net/t/1348623/amd-bulldozer-and-piledriver-overclocking-guide-asus-motherboard
http://www.ronwoods.us/2014/02/what-does-amd-application-power.html
this is a pretty good - easy to understand video:
https://www.youtube.com/watch?v=MckeAmnDeTk
however he's using a better motherboard.. some settings might be a bit difference but generally it's all the same|
also read this about the gigabyte motherboard - just don't take most of it too seriously -
the author has some pretty stupid complaints and he's also talking about the old blue "non-p" version
this board is actually really nice lookin' and feelin'
but he brings up one point about LLC that i'm also a bit pissed off about
- all settings have vdroop .. some bigger some smaller... only "extreme" prevents that - but it does so by dumping so much voltage it's crazy -
there needs to be a middle ground but there isn't ... 1.41v will be around 1.47 when cpu is under full load, 1.44 volts will go way over 1.5 etc. - it's crazy
http://forums.duke4.net/topic/6787-what-a-piece-of-shit-gigabyte-ga-970a-ud3-review/
this and the fact that the 2nd pci-express slot is only 4x are my only problems with this board...
but then again you buy a 990fx board for more pci lanes....
also if you'll buy only around christmas we might have some new choices out as well - i think intel's 5th gen broadwell processors will already be out by then...