New ram questions

pdc76

pdc76

New Member
ok, i have to replace my ddr 'cause i'm getting a new board and cpu. i've decided on ddr2 over ddr3. here's my setup:

qx9650 cpu
evga 780i motherboard

i want to put 4 gigs of ram in this board, but i can't decide on the speed. should i get the fastest it'll take (1200mhz)? or should i get 800 or 1066 so i can overclock? if i buy the fastest that the board can take, does that mean i can't overclock because it's already at the board's limit?

lastly, i want to match the speed with the fsb, which at stock is 1333mhz, but i will be overclocking. what speed should i get? i'm confused.
 
Well, the basic Idea would be that if you have 1200mhz ram... It's useless.

Your FSB needs to be twice as fast as the RAM to run at a 1:1 ratio. So for a 1333mhz FSB it should be 667mhz for the RAM. And if you want to use the full extend (1:1 ratio) of 800mhz RAM you need to run a 1600mhz FSB. And to use the full extend (1:1 ratio) of 1066mhz ram you need to run a 2132mhz FSB... Which is the next thing to impossible because that would mean a 533mhz bus-speed... Even for the best overclocking board that would be so hard to get.

I'd suggest you get a maximum of PC8500 (1066mhz) RAM and then underclock that to the correct speed. Or just buy PC6400 (800mhz) which is much cheaper and just clock your CPU to that...

For instance if you have a Q6600 with PC6400 DDR2 ram then you should run it at 8*400 for a 3.2Ghz Q6600 and a 1:1 ratio with the ram (or 7*400 or 6*400 or 9*400 whatever suits you).
 
i see, so if the board supports upto 1200, i can't overclock my memory beyond that? i guess i'll get the 800 and play with it. if i got 667, could i overclock the cpu more than i could with the 800?
 
You can, 1200 is a 'stock' sort of set. You set a multiplier to get it to 1200DDR and then you can still manually raise the FSB to get it to go faster than 1200DDR. It's hard to say if it will actually be able to handle going faster, the voltage is probably going to be 2.4V already.
 
looks like i'll just get some slower stuff. any recommendations? i wanna run 4 gigs, i saw 2 sets of reapers, 2x2gb each set, one is 1000mhz, one is 1066mhz. which would you get? like i said, it's gonna be put on a board with a qx9650 that i wanna o'c.
 
I'd probably go with the less expensive set, they are almost the same speed so it shouldn't make much difference.
 
I still might go with a ddr3 set. i haven't really decided on a board yet. cost is not an issue, the most speed i can get IS.
 
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