In terms of space around the CPU socket, I also measured and
compared between the 3 leading 680i SLI motherboards:

63 abit IN9 32x MAX 680i SLI Motherboard

The judgement process was to measure the biggest rectangle
around the CPU for a flat base that has nothing taller than the height of the
CPU. So if capacitors are taller than the CPU, the area is shrunk inwards to
clear these capacitors. Approximately, the space offered is:

Motherboards

abit
IN9 32x MAX
ASUS
Striker Extreme

Inno3D
680i SLI
(NVIDIA Ref.)

Socket
Space

10.2 x 10cm
10.5 x 9.5cm
7.6 x 10cm

The space offered on the Ref board is the least while Striker’s and IN9′s are
very comparable.