Hi, I am having a problem with a Centos 6.7 installation with the latest patches (2.6.32-573.18.1.el6.x86_64). The X server version is 1.15.0-36.el6.centos The motherboard is a SuperMicro X11SSV-Q. This is an i7-6700 CPU and Q170 chipset. It has a built-in intel graphics chip. The system works fine, until I plug in some combinations of USB hubs. For example, I have an 8 port USB 3.0 hub (based on the VIA chip), but also some combinations of USB 2.0 hubs also cause the problem. A single Terminus USB 2.0 7 port hub by itself is fine, but adding a second hub does not work. What happens is that the X server will not start. The relevant lines from the X log appears to be.. [ 561.239] (II) Loading /usr/lib64/xorg/modules/libint10.so [ 561.240] (II) Module int10: vendor="X.Org Foundation" [ 561.240] compiled for 1.15.0, module version = 1.0.0 [ 561.240] ABI class: X.Org Video Driver, version 15.0 [ 561.240] (II) VESA(0): initializing int10 [ 561.240] (EE) VESA(0): V_BIOS address 0x367f0 out of range [ 561.240] (II) UnloadModule: "vesa" [ 561.240] (II) UnloadSubModule: "int10" [ 561.240] (II) Unloading int10 [ 561.240] (II) UnloadSubModule: "vbe" [ 561.240] (II) Unloading vbe [ 561.240] (EE) Screen(s) found, but none have a usable configuration. [ 561.240] (EE) Fatal server error: [ 561.240] (EE) no screens found(EE) [ 561.240] (EE) Please consult the CentOS support at <a href=http://wiki.centos.org/Documentation>http://wiki.centos.org/Documentation</a> for help. [ 561.240] (EE) Please also check the log file at "/var/log/Xorg.5.log" for additional information. [ 561.240] (EE) [ 561.241] (EE) Server terminated with error (1). Closing log file. It is the V_BIOS address out of range that appears to be the problem. When I don't have the problem USB hubs installed, then the same section of the log file is fine.. [ 11.385] (II) Loading /usr/lib64/xorg/modules/libint10.so [ 11.385] (II) Module int10: vendor="X.Org Foundation" [ 11.385] compiled for 1.15.0, module version = 1.0.0 [ 11.385] ABI class: X.Org Video Driver, version 15.0 [ 11.385] (II) VESA(0): initializing int10 [ 11.385] (II) VESA(0): Primary V_BIOS segment is: 0xc000 [ 11.387] (II) VESA(0): VESA BIOS detected [ 11.387] (II) VESA(0): VESA VBE Version 3.0 [ 11.387] (II) VESA(0): VESA VBE Total Mem: 32704 kB [ 11.387] (II) VESA(0): VESA VBE OEM: Intel(R) SKL Mobile/Desktop Graphics Chipset Accelerated VGA BIOS [ 11.387] (II) VESA(0): VESA VBE OEM Software Rev: 0.0 [ 11.421] (II) VESA(0): Creating default Display subsection in Screen section "Default Screen Section" for depth/fbbpp 24/32 This happens whether the hubs are active at boot time (in which case the X server never starts), or if I plug the hub after booting, in which case if I log off, then the X server does not restart. Any help would be greatly appreciated. Thanks, ----------------------------------------------------- Russ Poffenberger | System Architecture Group Phone: +1 / 408 / 635-6049 russell.poffenberger@xcerra.com Xcerra Corporation, LTX/Credence Division 1355 California Circle Milpitas, CA 95035, USA -----------------------------------------------------