The microATX motherboard form factor typically has fewer PCI/PCIe slots compared to the ATX form factor. It fits into a shorter 2U chassis like the K239F. Consider the mini-ITX motherboard range if even smaller is needed. 

IMB-ADL-H610
microATX MB LGA1700 12th/13th Gen, DDR4, 3x displays, 2xLAN, USB 3.2
5,046.00 5046.0 ZAR Excl. VAT
IMB-ADL-Q670
mATX MB 12th/13th Gen, DDR4, Triple Display, 2x 2.5GbE LAN, M.2, USB 3.2
8,512.00 8512.0 ZAR Excl. VAT
MM02-12
Intel® Q470E Chipset, support LGA1200 10th Gen. CPU (Max 95W), DDR4 up to 128GB, 6* SATAIII support RAID, 2* M.2 M-key, 1* M.2 E-key, 4* USB3.2 (Gen.2), 2* GbE, 2* 2.5GbE
7,830.00 7830.0 ZAR Excl. VAT
MM10-Q6702
Intel Q670E chipset supports LGA 1700 socket for the Intel® 13th/12th Gen (Raptor Lake-S/Alder Lake-S) i9/i7/i5/i3 processor with DDR5-5600MHz/4800MHz up to 128GB memory, Support Max. 125W TDPs under 240A
7,375.00 7375.0 ZAR Excl. VAT
MS-CHALLENGER A10
M-ATX MB AMD A10-RX425BB Quad-Core 3.4GHz APU
2,060.00 2060.0 ZAR Excl. VAT