Matching Front Side Bus with Memory

[BobbyDigital]

I am absolutely lost when it comes to which type of RAM to buy. I'm building a new system with a Core 2 Duo E6300 or 6400 and the Gigabyte GA-965P mobo. What type of DDR2 Ram works best with this set-up? The specs on the motherboard say the memory standard is DDR2 800, is this the type of memory I have to buy? Could I possibly go with another type, say DDR 667, if not, why? Everything I have googled on the subject is either outdated or very confusing, what is the rule for matching memory/processor/mobo?

 

[moosey]

The FSB of those processors is 1066 (quad-pumped). Therefore, divide by 4 to get the true FSB of 267. To run at stock speed you'll need DDR-533 (which is 533/2=267). You can get anything over that also. Depending on prices and what you want to do, there are some good deals on DDR2-800. You can run the memory at the faster speed also and having faster memory will allow you to overclock the processor.

 

[zest]

Decent DDR 667 is the clever potion..

 

[magreen]

The way memory works is it clocks down to the speed of your system. The name the vendor gives it refers to the maximum speed it can do. But if you stick fast memory into a system with a slow FSB, the memory will be running at the slow speed of the FSB.

For example, memory that's called DDR2 800 can do a maximum speed of DDR 800, which corresponds to an FSB of 400 (DDR and DDR2 memory are double-pumped, which means they transfer data twice per cycle, which is why DDR speeds are reported as double the clockrate of the memory... FSB of 400 = memory clockspeed of 400 MHz = DDR 800, FSB of 266 = DDR 533, etc.). But if you stick that DDR2 800 into a stock Core 2 Duo system which has a 266 FSB, that memory will be running at DDR 533 speed. So to run a Core 2 Duo at stock settings, all you need is DDR2 533.

Now, if you wanted to overclock your Core 2 Duo up to a 333 FSB, for example, then your memory would be clocked to DDR 667 speeds. So you'd need to have memory that could do that speed. DDR2 800 memory allows you to overclock your system to 400 FSB.

There's also another thing called a memory multiplier -- it allows you to run your memory at a different speed than the FSB, instead of 1:1. That's called running the memory asynchronously. For example, your mobo might let you run the memory at a 5:4 ratio, meaning at stock speeds your FSB would be 266 but the memory would be running at 333 MHz which translates to DDR2 667 speed. 3:2 ratio allows DDR2 800 speed at stock 266 FSB. You get the idea.

Hope that helps.

 

[WoodButcher]

Originally posted by: magreen
The way memory works is it clocks down to the speed of your system. The name the vendor gives it refers to the maximum speed it can do. But if you stick fast memory into a system with a slow FSB, the memory will be running at the slow speed of the FSB.

For example, memory that's called DDR2 800 can do a maximum speed of DDR 800, which corresponds to an FSB of 400 (DDR and DDR2 memory are double-pumped, which means they transfer data twice per cycle, which is why DDR speeds are reported as double the clockrate of the memory... FSB of 400 = memory clockspeed of 400 MHz = DDR 800, FSB of 266 = DDR 533, etc.). But if you stick that DDR2 800 into a stock Core 2 Duo system which has a 266 FSB, that memory will be running at DDR 533 speed. So to run a Core 2 Duo at stock settings, all you need is DDR2 533.

Now, if you wanted to overclock your Core 2 Duo up to a 333 FSB, for example, then your memory would be clocked to DDR 667 speeds. So you'd need to have memory that could do that speed. DDR2 800 memory allows you to overclock your system to 400 FSB.

There's also another thing called a memory multiplier -- it allows you to run your memory at a different speed than the FSB, instead of 1:1. That's called running the memory asynchronously. For example, your mobo might let you run the memory at a 5:4 ratio, meaning at stock speeds your FSB would be 266 but the memory would be running at 333 MHz which translates to DDR2 667 speed. 3:2 ratio allows DDR2 800 speed at stock 266 FSB. You get the idea.

Hope that helps.

I'm getting a new board also so this helps me, I'm looking for big overclocks with my 6600. Just to be sure here is what I propose-
patriot 8500
http://www.newegg.com/product/product.asp?item=N82E16820220161
commando mobo
http://www.newegg.com/product/product.asp?item=N82E16813131149

Does anyone see any problems?
I looked at the dominator 10,000 but only a fast look, $650.oo Noooonononono, no.

 

[Roguestar]

Do a bit more research, because of the 6600's x9 multiplier you only need DDR2-800 to get an overclock of 3.6Ghz using a motherboard with P965 or 975X chipset that forces you to run memory at lowest 1:1 with FSB (which is both a huge overclock and not even guaranteed at that high rate, but likely).

Read these threads:
http://forums.anandtech.com/messageview.aspx?catid=28&threadid=1947261
http://forums.anandtech.com/messageview.aspx?catid=28&threadid=1966035

 

[engiNURD]

if you want to go past 3.6ghz, you'll want some oc'able ram. any ram on this list with micron ic's will oc nicely:
http://ramlist.ath.cx/ddr2/

off the top of my head, that includes buffalo firestix ddr2-800, patriot xp LLK ddr2-800, crucial ballistix ddr2-800/1000, and g.skill 2gbhz sticks. the commando is overpriced. the best overclockers are the 680i chipset based boards, then the p965 express boards like the p5b dlx, p5b-e, and ds3.

 

[zest]

Originally posted by: engiNURD
if you want to go past 3.6ghz, you'll want some oc'able ram. any ram on this list with micron ic's will oc nicely:
http://ramlist.ath.cx/ddr2/

off the top of my head, that includes buffalo firestix ddr2-800, patriot xp LLK ddr2-800, crucial ballistix ddr2-800/1000, and g.skill 2gbhz sticks. the commando is overpriced. the best overclockers are the 680i chipset based boards, then the p965 express boards like the p5b dlx, p5b-e, and ds3.

Superb link m8..

 

[WoodButcher]

I fixed my links, I was thinking the 8500 memory for a little more headroom, and yes, I intend to aim high, I'd like to get 4.0 I've been watching a thread at extreme systems http://www.xtremesystems.org/forums/showthread.php?t=125865&highlight=commando and this is the way I'm planning to go. Will the 8500 do better than the 8000 or will I run into compatibility issues? I'm not concerned about the slightly higher price just not having enough headroom.