older PC noob memory and bios help plzzz

[happyH]

Hi, my friend gave me his old PC bought from OCUK circa 2009. It is a Gigabyte MA790XT-UD4P motherboard a AMD phenom 2 X4 955BE. It had 4890 graphics but i have changed to Radeon 6950. the memory is CORSAIR CM3X2G1600C9DHX.
These are seated in slots 3 and 4 as the cooling fins wont go in slots 1 and 2.
THE PROBLEM.....
I bought 4 lots of Corsair CMX4GX3M2A1600C9 and when i install i can hear hard drive etc but get a blank screen. I know the memory is good as i have used them in identical motherboard and set up. Not that i knew what i was doing but i think i went in the bios and lowered CPU clock and a few other things and it worked!

So i need help with this one........i really don't know jack about bios and Overclocking.i know how to get in the BIOS but there are so many settings i don' really know what to change. i took photos set everything to auto and stuck the 4 chips in but still nothing. Obviously present set up was Overclocked by OCUK with the original memory.I know the memory are slightly different voltages etc. i think the original memory and processor are all overclocked.
Can someone help me to re set up the bios in really easy to understand terms to accept my 4 new chips of memory. happy to send a bottle of vino to anyone who can help
If someone can help would be really great..i can then play BF a bit better...well probably not!
many thanks
H

 

[happyH]

thanks for the advice, tried two sticks and the same result. as i said i have had these four sticks running in a standard non clocked motherboard that was exactly the same and they worked fine...hmm
thanks anyway

 

[happyH]

thanks Nkata i will try that later.
At present the CPU freq is 200. CPU clock ratio is x18 (3600hz).
Memory clock is set to manual memory clock X 6.66 (1333hz).
system voltage control is manual,
DDR3 volt control +0.2v (1.8v)
nBRIDGE +0.2 (1.3V),
SBRIDGE +0.2V (1.4V)
CPU NB VID TRL +0.175,
CPU voltage control +0.15.
Normal CPU Vcore 1.35v.
just wanted to check when you say the vram is that the DRR voltage which is at +0.2 (1.8v) .
I am a bit rubbish with the BIOS .....i can find everything but not sure what it all means!
many thanks
paul