Bad motherboard, try reinstalling drivers if you can even get that far. You could have multiple issues, maybe a bad OS install, missing files. Try reinstalling the OS.
Dell Optiplex GX620 Cooling Fan san ace 9g0812p1f031, Dell Optiplex 790 Desktop Cooling Fan K650T, Dell M6792 Dell M227c Optiplex 740 Front Case-fan Assy M6792 Y5299 Enclosure Anf, Dell Optiplex 740 745 755 SFF Hard Drive Caddy & Fan NH645, Dell 89504 Heatsink/ Fan Assembly For Optiplex Gx1, Dell K0546 Fan & Shroud For Optiplex, Dell WH001 Dell Fan Assy For Dimension 9200c/ Xps 210 / Optiplex 740 / 745 / 755, Dell Optiplex GX280 Dimension 8400 Fan & Shroud - T4307, Fan and Heatsink for Dell Optiplex GX60, Dell Optiplex GX520 GX620 Small Form Factor Fan M8788, Dell Optiplex 755 GX620 GX520 SFF CPU Case Fan M8788, Dell RR527 Optiplex 745 755 760 780 Mini-Tower MT Fan and Shroud, Dell RR527 Optiplex 330 360 Mini-Tower MT Fan and Shroud, Dell RR527 Optiplex GX520 GX620 Mini-Tower MT Fan and Shroud, Dell JY385 Optiplex & Vostro Heatsink & Fan, Dell 0K0456 Fan Shroud For Optiplex 170l K0456, Dell KDE1212PMV1 Optiplex 330/775 Dc 12v Fan & Shroud Assy, DELL C7018 OPTIPLEX MOTHERBOARD P4 3GHZ CPU & 512MB RAM & HEATSINK/FAN, Dell TJ160 Dell Fan Assy For Dimension 9200c/ Xps 210 / Optiplex 740 / 745 / 755, Dell P714F Optiplex 960 Mini Tower Cpu Fan 12v, Dell HK253 Optiplex 745 Hdd Fan Usff, Dell BG0903-B047 Heatsink & Fan Assembly Nmb For Optiplex Gx280 Sff M5786, DELL Optiplex GX745 USFF HDD Hard Drive Caddy w/ HK120 Fan Dell P/N: UU520, CPU Cooling fan and heatsink for Dell Optiplex GX 60 Part # 9G180, NEW Dell G958P OptiPlex 755 SFF SMALL FORM FACTOR Fan Assembly, San Ace/Dell Optiplex CPU Fan 80mm X 38mm w/Shroud M8041 9G812P1F041, Dell XC020 Optiplex Gx280 Fan & Shroud Assy., Dell 6P212 Optiplex Gx260 Heat Sink & Fan, Dell KG316 Fan And Shroud Assy Optiplex 745 Sff, Dell Optiplex GX520 GX620 745 755 760 SFF Case Cooling Fan P8402 M8788 , Dell RR527 745mt Fan & Shroud Assy Optiplex Smt, Dell Optiplex GX270 SFF Heatsink & Fan 9G180, Dell PD812 Optiplex Gx520/620 Fan Assy., Dell M8788 Optiplex Gx620 Cpu Fan Assy., Dell 9W999 Optiplex Gx260 Heat Sink & Fan Assy., Dell Optiplex 790 Desktop CPU Heat Sink FGW90 with 4-Pin Fan K6YMY, Dell 9G0812P1F041 Optiplex Gx520 Fan Assembly 12v/0.58a, Dell N1240 Heatsink W/ Fan For Optiplex 270 Sff / 620 2.8, DELL Optiplex GX280 Heatsink & Fan Assembly Dell P/N: ND186 Genuine/OEM TESTED, Dell Optiplex GX620 AVC Desktop SFF Fan & Speaker DA08038B12H TESTED, Dell Optiplex 960 Desktop DT Processor CPU Fan & Shroud G259F XX580 CP541, Dell Optiplex GX280 Dimension 4700C Blower Fan T2607, Dell Optiplex 745 755 760 SFF Case Fan HU540 P8402, Dell Optiplex 755 Small Form Factor Fan P/N HU540, Lot of 2 Dell Optiplex 745/755 CPU case SUNON 5.2W Cooling Fans OU8679, Dell Optiplex GX150 Tower CPU Fan w/ Shroud 6G180 1G456, NMB 3612KL-04W-B66 CPU fan Dell Optiplex GX280 GX400, Dell CPU Case Fan Optiplex GX240 GX260 GX270 , Dell K0456 Optiplex 170L/Dimension Fan/Shroud Assembly, Dell Optiplex GX280 MB H8164 +CPU(521 SL8HX 2.8GHZ) HeatSink FAN + Board Holder,
