Re: New processor overheating
Stock coolers can let those processors get quiet toasty...
The case looks to be rather cheap, solid top, only a 92 or 80mm rear exhaust fan if you install one?
Get you a good highflow fan on the rear of that case. What thermal paste are you using?
What does your BIOS report for temperatures at IDLE?
That aside, Positive pressure is a bad idea in most cases, it's only beneficial in open air like cases where it's mostly a mesh style side paneling and rear, because of the massive mesh area your "positive" pressure is still neutral, the air has somewhere to go. If it can't go anywhere in a regular case, it just turns into warm or hot air.
Positive = Only good in a Mesh style case
Neutral = Best bet for most cases.
Negative = Best bet in "sealed" cases, such as ones that do not have a vented side panel.
Also, finish securing that motherboard to the case! The screw holes are used as ground points, and for board rigidity.