If you do not have a cut-out for rear access to your motherboard, the only way you can install an aftermarket CPU cooler is if the CPU cooler uses the stock backplate.
The A30 Freezer uses the stock AMD backplate, but requires different retention brackets for mounting. So, without removing your motherboard, you can remove the stock retention brackets and install the A30 retention brackets so you can mount it.
I will admit that I had forgotten that AM3+ platforms can have two types of retention brackets; square and separate. ASUS only uses the square type in their 78-models of current offerings. The more advanced models (like what you and I have) use the separate/two-bracket style: http://www.ebay.com/itm/AMD-Motherboard-AM2-AM2-AM3-FM1-Socket-940-FM1-Retention-bracket-Holder-Clip-/251275256190
Those are the style of brackets which your motherboard has; you can unscrew one bracket at a time to ensure you don't somehow lose your backplate behind your motherboard - assuming you have the room behind your motherboard for that to happen.