Meines wissen nach ist XL-ATX nicht standardisiert wie ATX.Hersteller unterschiedler Firmen wie(EVGA,Gigabyte,MSI)haben ihre eigene Boards mit unterschiedlen Abmaßen herraus gebracht(Außenmaße).
Jetzt ist die frage ob die Bohrlöcher bzw.Lochabstände auch irgendwie davon beeinflußt ist?Eine Aussage bei Wikipedia über XL-ATX,
The name "XL-ATX" has been used by at least three companies in different ways.
In September 2009, EVGA Corporation had already released a 13.5 × 10.3 in (343 × 262 mm) "XL-ATX" motherboard as its EVGA X58 Classified 4-Way SLI.[6]
Gigabyte Technology launched another XL-ATX motherboard, with model number GA-X58A-UD9 in 2010 measuring at 13.6 × 10.3 in (345 × 262 mm), and GA-X79-UD7 in 2011 measuring at 12.8 × 10.0 in (324 × 253 mm). In April 2010, Gigabyte announced its 12.8 × 9.6 in (325 × 244 mm) GA-890FXA-UD7 motherboard that allowed all seven slots to be moved downward by one slot position. The added length could have allowed placement of up to eight expansion slots, but the top slot position is vacant on this particular model.
MSI released MSI X58 Big Bang in 2010, MSI P67 Big Bang Marshal in 2011, MSI X79 Xpower Big Bang 2 in 2012 and MSI Z87 Xpower in 2013 all of them are 13.6 × 10.4 in (345 × 264 mm). Although these boards have room for additional expansion slots (9 and 8 total, respectively), all three provide only seven expansion connectors; the topmost positions are left vacant to provide more room for the CPU, chipset and associated cooling.
Aber vielleicht ist das was du benötigst,sollte der Link gehen.Da sind die Abmaße für MSI X Power Z87 Board dabei,
https://dl.dropboxusercontent.com/u/6774673/OCFORUMS/RampageBlackBoardTemplate.pdf
grüße Brex