Why is my system unstable when I lower the memory frequency?

[Fadardo]

My current OCZ DDr2 800 Platinum rev2 memory(based off the PROmos chip) is only stable @400mhz and OCed up to ~450mhz(ddr2 900)

and when I try to lower memory frequency to 333mhz(667) then overclocking till the memory reaches 388mhz(777) its unstable. I don't know why that would be.

Yet when I lower it even further to 266mhz(533) (1:1ratio) then overclock it to 309mhz(618) it is stable.

Timings are set by the mobo to standard timings such as 5-5-5-15 at 400mhz and I don't see a way of changing that in the bios.

So I assume this is a memory issue and I should be getting new memory.
Would D9G chip memory be what I need to achieve a 3.4ghz frequency? Could I get ram for under $100 after shipping that would be good enough?


(One problem I noticed was my mobo only allows me to incrase the fsb to 500mhz so maybe I need a new motherboard as well.)

 

[sutahz]

Could be your FSB/NB limited.
Could be the board is auto adjusting your memory incorrectly
Could be your not adjusting Vddr properly

 

[Fadardo]

I don't think its a fsb/nb limit my board got great recommendations all around and for overclocking from tom's hardware and got praise from Anandtech mobo year end roundup this december.

Vddr? I'm not overclocking my pci bus or the video card itself. Everything is at factory default.

Originally posted by: sutahz
Could be the board is auto adjusting your memory incorrectly

How can I manually adjust my timings then?
There is no option in BIOS...