Bios not booting with new psu

[rnnoob]

hey guys
i just got a new power supply yesterday
the corsair gs600w
as of now my specs are
amd athalon 64x2 6000+
Jetway m26gt3-svp(integrated 6100)
3 gb transcend ddr2 667mhz sdram single channel
HIS HD 5670 1gb ddr3
Hitachi 160gb hdd(pretty old)
Seagate Barracuda 1TB hdd(bought it with the psu)
realtek Ethernet port pci.

earlier i was running the system on a 450 w local brand psu, but due to frequent bsods and as i was gonna put a new hdd i thought i'd change the psu as well
now the PROBLEM
i installed the psu and the hdd in my cabinet yesterday and i got the common problem of the bios not booting up
so i removed the ram checked it
removed the graphics card checked it
reset CMOS
and tried booting up with only the cpu mobo and ram connected
NO LUCK..the cabinet and cpu heatsink fans were spinning the blue led in the psu was glowing as well
now when i connected the old psu the system booted normally the bios started and all that

so whats the problem? is the psu incompatible with my mobo or what?
my mobo has a 24 pin connector and a separate 8 pin connector for the processor
the old psu had a 24 pin and a 4 pin connector the cpu ran fine
the gs600 has a 24 pin connector and a 4+4 pin connector
i tried connecting only the 4 pin and 24 pin as well as the 8 pin and 24 pin (and im not dumb that ill connect the pci-e pin in the cpu slot seriously guys, i know what im doing) still nothing
the only difference in the psu connectors is the 24 pin molex of the newer psu dosent have the white -5v rail on it(im not surprised) but the old one has it, so can it be a problem
i know the -5v rail is only used for the old ISA bus and i dont think that the motherboard has one.

so please help me and tell me whats the problem. is the psu faulty or is it incompatible?

 

[GhislainG]

The -5V definitely isn't required. Use a DVM to check all voltages or test it in another system. If all voltages are correct or if it works fine in another system, then the PSU may be incompatible with the motherboard. A quality 380W PSU would have been enough for that system.

 

[rnnoob]

well i dont have a DVM and unfortunately ill not be able to access the computer for a month now cause my vacation ends today and have to leave town for college tomorrow. so most probably ill give it to a computer shop for checking.
and GhislainG are you sure a 380w power supply would suffice, i doubt it. I chose this psu as i need enough headroom for oc and future upgrades as even tough its not my primary pc its what i have to make do with when im home

and in case of incompatibility can u please elaborate as of why a PSU can be incompatible to a motherboard.. i used to think that mostly all psu are standardized??