asus p5e3deluxe, e5200, hd3870 no boot
 

Hi,
i bougt some new computer gear from piotke today but i ran in some troubles while bootin.
specs:
intel e5200
asus p5e3 deluxe
2x1gb pc3-10660(ddr3)
ati HD3870
i tested with 2 psu's, ultrax connect 500x and antrec trueblue 450w.
both psu's have a 20pins atx molex and 4pins molexes.
My motherboard on the other hand has a 24pins and a 8pins connector.
When i connect the 20pins molect with the 24pin socket and a 4pin molex with the 6pins socket my pc only boots for less than a second
When i dont connect the 4 pin molex (so that no molex is connected with the 8pin socket) all fans start spinning but i dont get an immage on my screen (screen stays in strandby)
i tried:
-booting without hdd, dvd etc.
-using only one ram module and tried every ram slot.
-tested graka in both pcie 16x slots
-clearing the bios
So my main question is if these problems are coused by not having 24pins and 6pins molexes or somthing else.
If coused by someting else do you guys have any ideas what might couse my problem?

Manny thanks in advance!

You did not forget to power the VGA card also ?