Newly built PC wont POST.. PLEASE HELP!

[mobusta1]

Here is what I bought a few days ago and installed it today

SAPPHIRE 100243L Radeon HD 4870 512MB 256-bit GDDR5 PCI Express 2.0 x16

1 GIGABYTE GA-EP43-DS3L LGA 775 Intel P43 ATX Intel Motherboard - Retail

1 G.SKILL 4GB (2 x 2GB) 240-Pin DDR2 SDRAM DDR2 1000 (PC2 8000) Dual Channel Kit Desktop Memory Model F2-8000CL5D-4GBPQ

1 Western Digital Caviar SE16 WD6400AAKS 640GB 7200 RPM SATA 3.0Gb/s Hard Drive - OEM

1 Antec Nine Hundred Black Steel ATX Mid Tower Computer Case -

1 Intel Core 2 Duo E8400 Wolfdale 3.0GHz LGA 775 65W Dual-Core Processor

1 XIGMATEK ACK-I7751 Retention Bracket

1 XIGMATEK HDT-S1283 120mm Rifle CPU Cooler - Retail

1 CORSAIR CMPSU-750TX 750W ATX12V / EPS12V Power Supply - Retail

This is the first time I've ever built a computer myself. It turns on fine so I dont think its the PSU, the LEDS on the MB light also. I've taken out one stick of ram than swapped it and even took out both sticks of ram but the PC still wont make a beep noise when I turn it on. I have no clue what to do. Anyone please save me

 

[CHECKUP]

ther e r 2 power inputs for the mobo. one is a 4 or 6 or 8 pin connector the other is the 20 to 24 pin connector. see if both of these r properly inserted.

 

[mobusta1]

Do both of them need to be connected? I dont see a 4 pin MB connector on my PSU. The computer boots up fine but it just wont POST.

EDIT:

THANK YOU!!!!! The comp actually posted now. But i had to get an 8pin and only put in 4 pins.. Is this ok?

 

[CHECKUP]

my evga 680 uses a 8 pin connector. i would call gigabyte tech service and ask them as to the need for the 8 pin or 4 pin. have fun with your new toy

 

[samsonJS]

My EP45-DS3R takes the 8-pin as well, if you're computer is working you're good to go! Nice machine, have fun!