What rig are you using this PSU for? If it's the one in your signature, that only requires ~600W.
(meaning a 600W PSU would be at ~50% load when the system is at 85% load)
Here are the glaring differences I see:
- The AX has two 4+4 pin power connectors for rediculus overclocker boards like this
whereas the HX only has one. (these are used to feed power to the CPU)
- The AX is fully modular, you can remove the 20+4 pin power connector if you wish. (not sure why anybody would need to do that, its hard to run a computer without power to the mobo)
- The AX has a slightly higher efficiency rating @ ">90%" (Since 80 Plus Gold is 90% and 80 Plus Platinum is 92%, the difference between that and the HX is small)
- The HX is a bit longer at 7.09" Not sure if this is the dimensions of the box or its just longer because of the 20+4 pin wires that stick out the back that can only be bent so far. 3/4" reduction for the fully modular AX seems like a reasonable explanation of the latter theory.
- The HX has a 140mm fan while the AX has an "ultra quiet" 120mm fan. The general rule says that the bigger the fan, the quieter it is; so I would imagine they would be acoustically equal.
Honestly, from what I'm seeing, I would go with the HX model. With the current $10 promo code, you'll get it for $115 after MIR. Sounds like a good deal to me.
i5-3570K, ASRock Z77 Pro4-m, Asus GTX660 TOP, 120 GB Vertex 3 Max IOPS, 2 TB Samsung EcoGreen F4, 8GB G-Skill @1.25V, Silverstone PS07B