Ther CPU runs really hot, you need a really good cooler for it as well as internal fans.
The Asus site doesn't have a spec sheet for the motherboard (it doesn't show) so here are the specs from elsewhere -
http://www.pureoverclock.com/Review-detail/combo-review-amd-vishera-fx-8350-asus-crosshair-v-formula-z-rog/5/
The PCIe slot is only verison 2.0 so a version 3.0 video card would revert to a slower speed bandwidth reducing its performance.
It's a rather small motherboard and you might be using a rather small case, it could be that airflow is an issue.
The motherboard has a "Start" and "Reset" button on it, for testing purposes like breadboarding, you should consider using them to see if your system boots, it might be that your Power button connector (on the case) is the wrong type, usually they are 2-pins but some older cases have a 3-pin connector.
Edit -
The Asus UK site has the QVL lists and specs -
http://uk.asus.com/Motherboards/AMD_AM3Plus/CROSSHAIR_V_FORMULA/#specifications
What speed, voltage is your ram?
If possible could you post a pic of your PC case innards?