What difference? I see none except they say the X58A-UD5 has "Dual" GbE LAN and the X58A-UD3R has "2" GbE LAN. So if they are identical except for that I'd rather save the 60 bucks and get 2 LAN instead of dual LAN.
X58A-UD5 also has compared to the UD3R:
Advanced 12+2+2 power phase design with VRD 11.1 support
Onboard Debug LED display simplifies motherboard troubleshooting
2 Gigabit Ethernet LAN with Teaming functionality
Power/reset/Clr CMOS onboard button for easily operation on the workbench
I was wondering the same exact thing. I couldn't really find a difference. The comparison sheet on Gigabyte's website showed all the same specs for both. I ended up going with the UD3R since it was quite a bit cheaper.
The UD5 has (much) better northbridge cooling, for better overclocking.
The UD5 has another GbE port.
The UD5 has better power power management (8 phase for UD3R, 12+2+2 for UD5).
The UD5 has a POST Debug LED light.
The UD5 and UD3R both have power/reset/clear cmos buttons (I believe).
But is the UD5 worth $50-60 extra? I don't know...
Any one know how well the dual lan ports performs on the UD5. Are they good quality? I plan on purchasing it and was wondering if it is worth getting the UD3R instead and buying a separate lan controler.