New Build - cant get past post gigabyte GA-MA790X-DS4 phenom x4 9950 4

Hope someone can help - first build in along time and it aint working

MB - gigabyte GA-MA790X-DS4
cpu: phenom x4 9950
mem : 4gb OCZ gold series 1066 ddr2
graphics 8600GT 512mb
hdd: sata 3gb/s unformatted
psu : 425w

I get to post and can enter bios (no speaker so cant tell post test) then just get flashing white cursor top left off screen and does no more

I have no floppy drive, and cant boot from cd-rom

hav e tried a win xp discx and a ubuntu live cd but does'nt get past the flashing cursor.

cd spins up and appears to function fine

any ideas?

thanks for response

psu is an akasa hi-performance designed for AM2 and was advertised as suporting this rig - but the box doesnt mention phenom or AM2+ unfortunately no alternative to hand but everything seemed powered up and running (all fans/ cd-drive / graphics/ usb ports)

I did manage to flash to latest bios but made no difference

I can change bios settings happily but no matter what, just goes to the flashing white cursor once proceeding to boot stage as if cant recognise anything to boot from.

Have checked boot media in other machines and even setup a ubunutu bootable live usb key (managed to flash bios from usb key so know it can read it) but again nothing.

I've reset cmos to make sure nothing funny there and tried again.

everything reports as healthy and temperture are fine - things are working and getting warm

I'm getting another mobo today so will be able to compare, and will look at another psu as well

thanks for pointers

no worries

I've got the normal 1st boot 2nd boot third boot options and have tried all combinations (includes options for usb-zip usb-hdd as well as standard cd hd)

Also has a separate boot priority with only three preset options referring to differnt hds but have tried all combinations of this as well - in conjunction with the 1st boot etc