Re: asrock 970 extreme3 - wont boot at all
1st thing I do when building a new rig is to build it outside the case.
Then do as Chozo4 suggested - start with processor+heatsink/fan, powersupply, and Ram.
I use a momentary sw to start but you can short the 2 pins on the front panel header (PWRBTN# and GND). You only have to touch the 2 pins for a fraction of a second. See page 27 in the manual - ASRock > 970 Extreme3
If it works outside of the case then make sure the brass standoffs are aligned with the mounting holes in the motherboard. Yours is an MATX motherboard and uses only 7 mounting points.
I've run some of my builds outside the case for weeks before installing in a case.
My HTPC -
ASRock 970 Extreme3
AMD FX-4100 w/Coolermaster GeminII S cooler
M Station HT-1100 HTPC Media Center case
Antec 480 NeoPower PSU
Kingston HyperX Blu 8GB KHX1600C9D3B1K2/8GX
Gigabyte GV-R467ZL 4670/1GB video card
Hitachi HDS721050CLA362 500GB SATA hd
Windows7 Ultimate x64 & Ubuntu 10.04 LTS (partitioned)
Pioneer DVR-215D SATA DVD burner
Samsung 40" 1080p 120Hz LCD HDTV LN40C630
You can teach an old dog; it just takes longer.