Another question about RAM and CPU bus

S

SquiggDoggs

New Member
Okay...so if I had a processor with 800MHz FSB then ideally I should use
DDR2 800 RAM (I'm running dual channel) because DDR2 800 / 2 = 400MHz...and with them both it equals 800MHz wich is the FSB of the CPU...and this 1:1 ratio is desired...what I was wondering about was as follows...I would like to get a P4 3.4GHz processor (for cost purposes) but from what I can see anything this high in GHz only comes with a 800MHz FSB...correct me if I'm wrong...I don't wanna spend the money on DDR2 800 RAM and would like to get something like DDR2 667 or lower to save some money...this would not match the 800MHz FSB of the CPU and at the moment I can't find a processor that has a 667MHz FSB...can I underclock using BIOS...if so what would I need to do to match them...again thanks for the help
 
SquiggDoggs said:
because DDR2 800 / 2 = 400MHz...and with them both it equals 800MHz wich is the FSB of the CPU...
Click to expand...

What??? I have no clue what you're trying to say there... Being 1:1 with the processor really makes no difference. If you search around, many people say there is little performance difference between 667MHz RAM and 800MHz RAM. Unless it's about the same price, I'd just get 667MHz.
 
The speed of the cpu would be set by the fsb in a sense. With the 667memory installed the cpu would run at the slower speed A board that runs DDR2 800 ram generally will also take the 533 or 667mhz memory as well. You have to look over the specifications on a Socket 775 board you choose to see what memory as well as cpu it supports.
 
could you explain to me how the FSB determines the CPU speed...im trying to figure this whole memory and CPU thing out...don't seem to have it down yet...ive read that you want a 1:1 match but now im being told you dont need to...so im starting to get lost...respond back when you can...im up for any good websites or books on the topic...something that can help me better understand
 
You don't absolutely need a 1:1 match, it's just with a P4 it's better and cheaper to do so. Neither 800 or 667 run at a 1:1 ratio (800 will if you install it single channel but your board caps at 667 doesn it?). You can also use 667 and set it to 200 if you want.

You CPU speed is determined by the FSB and the CPU multiplier (ie. 200 x 18 for a 3.6GHz P4)
 
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