Headless/Headful running problem

[urilabob]

I have a small fedora-based (fc7) cluster; the client hardware is Sung ju tangos - I think these were sold in the US under the name AOpen MiniPC, but I'm not sure which model number, maybe 915. They are based on a 1.4G celeron cpu (couple of years old now, but still working fine). The clients are installed using pxe, but boot from the local drive, into runlevel 3. However I have one annoying problem with them:

.if a client boots with USB keyboard/mouse and monitor attached, then I can subsequently re-attach the keyboard/mouse/monitor and use them as a console to fix any problems that may have arisen on that client, even if the problem takes the network interface with it

.however if a client is booted without the keyboard/mouse/monitor attached, then when I attach the keyboard/mouse/monitor, the monitor stays black

.I think the problem lies with the monitor rather than the keyboard/mouse: if I get into a client via the network, I can see the normal interrupts in the logs when I attach/detach the keyboard and mouse in /var/log/messages, but I can't see any info about the attach/detach of the monitor (though I'm not sure where to look for this)

.it's not dependent on the monitor type - I get the same problem using two completely different monitors, one LCD-based, the other a CRT

.it doesn't seem to be a specifically fedora problem - the same problem arises on these systems with both ubuntu and f7

.I think it _does_ depend on the video card - the problem does not arise on another system using an old intel desktop, using a virtually identical f7 installation: I can boot it headless, but in runlevel 3, USB keyboard/mouse and monitor are immediately detected when they are subsequently added

Does anyone have any suggestion as to how to fix the install for the future, so that, even if a keyboard/mouse/monitor aren't present during boot, they can subsequently be connected (in text-only mode - I don't need a windowing interface); of course, it isn't feasible for me to boot them all with these connected at boot time - rebooting the cluster would take hours

TIA for any help

cpuinfo:
processor : 0
vendor_id : GenuineIntel
cpu family : 6
model : 13
model name : Intel(R) Celeron(R) M processor 1.40GHz
stepping : 8
cpu MHz : 1396.715
cache size : 1024 KB
fdiv_bug : no
hlt_bug : no
f00f_bug : no
coma_bug : no
fpu : yes
fpu_exception : yes
cpuid level : 2
wp : yes
flags : fpu vme de pse tsc msr pae mce cx8 apic mtrr pge mca cmov pat
clflush dts acpi mmx fxsr sse sse2 ss tm pbe nx up
bogomips : 2794.69
clflush size : 64

lspci output:
00:00.0 Host bridge: Intel Corporation Mobile 915GM/PM/GMS/910GML Express Processor to DRAM Controller (rev 03)
00:02.0 VGA compatible controller: Intel Corporation Mobile 915GM/GMS/910GML Express Graphics Controller (rev 03)
00:02.1 Display controller: Intel Corporation Mobile 915GM/GMS/910GML Express Graphics Controller (rev 03)
00:1d.0 USB Controller: Intel Corporation 82801FB/FBM/FR/FW/FRW (ICH6 Family) USB UHCI #1 (rev 04)
00:1d.1 USB Controller: Intel Corporation 82801FB/FBM/FR/FW/FRW (ICH6 Family) USB UHCI #2 (rev 04)
00:1d.2 USB Controller: Intel Corporation 82801FB/FBM/FR/FW/FRW (ICH6 Family) USB UHCI #3 (rev 04)
00:1d.3 USB Controller: Intel Corporation 82801FB/FBM/FR/FW/FRW (ICH6 Family) USB UHCI #4 (rev 04)
00:1d.7 USB Controller: Intel Corporation 82801FB/FBM/FR/FW/FRW (ICH6 Family) USB2 EHCI Controller (rev 04)
00:1e.0 PCI bridge: Intel Corporation 82801 Mobile PCI Bridge (rev d4)
00:1e.2 Multimedia audio controller: Intel Corporation 82801FB/FBM/FR/FW/FRW (ICH6 Family) AC'97 Audio Controller (rev 04)
00:1f.0 ISA bridge: Intel Corporation 82801FBM (ICH6M) LPC Interface Bridge (rev 04)
00:1f.1 IDE interface: Intel Corporation 82801FB/FBM/FR/FW/FRW (ICH6 Family) IDE Controller (rev 04)
00:1f.3 SMBus: Intel Corporation 82801FB/FBM/FR/FW/FRW (ICH6 Family) SMBus Controller (rev 04)
01:03.0 FireWire (IEEE 1394): Agere Systems FW323 (rev 61)
01:06.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL-8169 Gigabit Ethernet (rev 10)