Which Memory for Q8200 Build

[jfurterer]

I'm building a machine around a Intel Q8200. I've already selected my mother board which has a front side bus of 1333mhz the same described by the Q8200. I DO NOT plan to over clock but rather run everything at stock speeds.

What is the highest ram speed I would need for this system?
533, 667, 800, 1066 are all supported by the board.
Will their be any performance increase with faster ram?

Thanks in advance.

EDIT: I just did some research and here is what I've gathered, please let me know if this is incorrect.

The Q8200 has a reference clock speed of:333mhz and a Multiplier of 7 producing the 2.33ghz Clock Speed, is that correct?

When the "Divider" is gathered from my CPU speed viva: 2330/6 (6 being the smallest number that produces a result less or equal to 400mhz for DDR2-800) which would result in = 388.33mhz or 776mhz effective, my DDR2-800 would be underclocked to 776mhz?

OR Would the DDR2-800 be clocked down to 667mhz because my FSB speed is the same as my CPU reference clock speed of 333mhz?

 

[GhislainG]

DDR2-800 will run at its rated speed of 800Mhz (2 x 400). If need be you can set the speed, timings and voltage manually. DDR2-1066 is overclocked DDR2-800 memory that provides a minimal performance increase, if any.

You wrote that the CPU multiplier is 7, but then you used 6 as the divider. When Speedstep is enabled, the multiplier is lowered to 6 at idle and increased up to the maximum multiplier when the CPU is busy enough. Speedstep doesn't change the FSB, only the multiplier and indirectly the CPU speed.

 

[jfurterer]

As far as I've been able to discover the CPU multiplier for the Q8200 is 7. However the CPU multiplier is not the same thing as the divider used by the ram. If you have your RAM set to DDR2-800 the ram is assigned a divider that A. must be a whole number, B. must not exceed the ram actual ram speed (not effective, AKA: 400mhz for DDR2-800, 333mhz for DDR2-667, 267mhz for DDR2-533).

I understand how speedstep works, but this is not my concern. Rather it's whether or not the DDR2-800 will run at 776mhz or 667mhz. If it's the later then clearly I'll save $8 and buy the DDR2-667. However if the DDR2-800 can get effective performance at 776mhz I'd go with that. My confusion is as to whether the DDR2-800 running at 776mhz effective would actually see the 109mhz gain or whether it would be clocked down to the speed of my front side bus 333mhz (1333mhz effective) which translates to 667mhz effective DDR2 RAM.

 

[jfurterer]

I think I've answered my own question here but would like some confirmation. Because the Q8200 runs at a FSB of 333mhz the highest speed I could effectively achieve would be 667mhz without any over clocking. Since FSB clocks down to slower memory and memory clocks down to slower FSB 800mhz memory would clock down to 667 to accommodate the 333mhz FSB. Can anybody confirm this?

 

[GhislainG]

I think I've answered my own question here but would like some confirmation. Because the Q8200 runs at a FSB of 333mhz the highest speed I could effectively achieve would be 667mhz without any over clocking. Since FSB clocks down to slower memory and memory clocks down to slower FSB 800mhz memory would clock down to 667 to accommodate the 333mhz FSB. Can anybody confirm this?

It just means that the FSBRAM ratio will not be 1:1 if the memory is automatically detected at 800Mhz (it should), but you can manually set it to 667Mhz if you want to.

 

[jfurterer]

I see, but doesn't that mean that there would be a bottle neck at my fsb then? Meaning I wouldn't be taking advantage of the DDR2-800 because it runs faster then my fsb?

 

[average joe]

Here's my sloppy half forgotten opinion.

Having an asycronous ram speed (not 1:1) ratio does introduce wait states in the bus where either the cpu or the memory has to pause and let things catch up. This does slow down the memory transfer rate. However if the increase in memory speed is sufficeint, it will more than make up the for the wait states.

So if the ram is fast enough it will overcome the latency imposed by the wait states and you will see a net gain in performance.

going from
533 to 667 is 1% faster
533 to 800 is 2% faster
533 to 1066 3% faster

 

[GhislainG]

I see, but doesn't that mean that there would be a bottle neck at my fsb then? Meaning I wouldn't be taking advantage of the DDR2-800 because it runs faster then my fsb?

As Average Joe said, your system will be approximately 1% faster at 800 than it would be at 667 and it's free. If you need a bit more speed, then use mild overclocking, i.e., slightly increase the FSB. You can leave the memory at 667 (1:1 ratio) and increase the FSB to 400. Then your RAM will run at 800. Just make sure the CPU doesn't overheat - if it does, the system will shutdown to protect itself.

 

[liviu81x]

I have a system with e8400, 1333 FSB with 333x9 and DDR2 at 800 Mhz, that translating to a 12:10 DRAM - FSB ratio. I increase the CPU FSB sometimes to 400 (from 333) and use 1:1 parity, which is a performance gain only for the CPU.

How is your system working now ?