E6750 ram curiosity !

[cascade]

Hi there!

I've been planning a new system recently, and am looking at the C2D E6750 on a P35 chipset, probably the Gigabyte P35-DS3P.
I'm completly new to Intel and havent been able to find a specific answer after hours of trawling!
Basically, i dont intend to overclock, initially anyway, but have been looking at DDR2 6400 incase i want to in future.
As far as i can tell, a FSB:RAM ratio of 1:1 is nice? but running these two at stock, wouldnt give that.
Would the ram auto-downclock? to...667? or would they happily run at their independant speeds? and would that impact performance?

In honesty im a bit confused as to the best course of action

Any advice / clarification / suggestion would be greatly appreciated!

cheers!

[staffsMike]

If you run 1:1 then yes the ram will underclock to 667mhz.

If you run a different memory divider then the ram will run at stock speeds as will the CPU I believe.

[cascade]

Ah, thanks!
So its faily automatic then, via bios? (sry, ive never really messed with ram timings etc)
Just makes more sense to get this C2D, but the 8500 ram is just pointlessly expensive atm.

You think it'll run ok then? and wont just spit at me?

[staffsMike]

lol it will be fine with anything which is pc5300 or above. It will work automatically whether it auto's to 1:1 or uses a divider to use all the ram's speed.

It's fairly easy to adjust in most bios's anyway.

[cascade]

Sounds good
Many thanks for your replies, im sure i'll call again once i inevitably botch it up! hehe

ta!

[aidanjt]

Hi there!

I've been planning a new system recently, and am looking at the C2D E6750 on a P35 chipset, probably the Gigabyte P35-DS3P.
I'm completly new to Intel and havent been able to find a specific answer after hours of trawling!
Basically, i dont intend to overclock, initially anyway, but have been looking at DDR2 6400 incase i want to in future.
As far as i can tell, a FSB:RAM ratio of 1:1 is nice? but running these two at stock, wouldnt give that.
Would the ram auto-downclock? to...667? or would they happily run at their independant speeds? and would that impact performance?

In honesty im a bit confused as to the best course of action

Any advice / clarification / suggestion would be greatly appreciated!

cheers!

You don't even need to think about the divider, the BIOS will figure this out by itself via SPD (Serial Presence Detect), most modern RAM modules have this little chip that gives module configuration/characteristic information to the BIOS on boot.

Now, to look at things a little deeper, DDR memory works by delivering 2 bits of data per clock cycle, that means if the memory frequency is 200Mhz, the effective clock rate is 400Mhz. Intel's front side bus (FSB) on the other hand works at Quad-data rate, or 4 bits of data per clock cycle, so 200Mhz FSB delivers an effective clock of 800Mhz. Sometimes BIOSes use actual clock, sometimes effective clock, it's misleading annoyance, I know, but such is the market (they like to sling buzzwords and impressive numbers about).

Lets break down the characteristics of the E6750:
FSB Clk: 333Mhz
Eff. FSB Clk: 1333Mhz
Multiplier: 8
Internal Clk: ~2665Mhz (2.66Ghz)

And lets have a look at PC2-6400 (DDR2-800) Memory:
Mem Clk: 400Mhz
Eff. Mem Clk: 800Mhz

See the difference?.. Intel's FSB may have a lower actual clock, but the amount of data it delivers is higher than that of PC2-6400 memory, but it's the actual clock that is being divided, so if you use a 1:1 ratio, you're actually underclocking your memory to an effective 666Mhz, clearly that's going to hurt when it comes to memory transactions. So you want a ratio of about, 3:5 (or close to that) to get your memory clock to normal specifications, but you might notice that there's a 533Mhz gap between the CPU and memory.. While the hardware on your system does need breathing room to communicate with the CPU, a lot of hardware talks directly to the memory controller, and the CPU needs to do plenty of RAM transactions as well, so sometimes even 800Mhz isn't enough for memory modules. However mileage varies, so it's up to you if you want to stretch the budget to PC2-8500 modules.

[cascade]

wow, very helpful information there aswell, many thanks.

Would i be right in saying then, that if i just settled for the E6600 C2D instead, things would be a good bit less complicated? And all the ratios / clocks etc would match up?
I just fear for compatibility / stability and usefullness. Have made costly mistakes in the past

[staffsMike]

I just fear for compatibility / stability and usefullness. Have made costly mistakes in the past

Havn't we all

The E6600 makes no more sense compatability wise really.

My motherboard runs unlinked FSB's so I can run the CPU and RAM seperatly at whatever speeds i like which is a nice touch on nforce boards..it's a nice way to overclock without all these complications lol

The E6750 and PC6400 will be fine together. If you don't want to overclock then the easiest thing to do is just get 667mhz ram and run 1:1 and be done with it. You would be hard pressed to notice the difference i'm sure.

If you get pc6400 try running a divider as above otherwise it will be wasted speed.

[-N!CK-]

crucial ballistix pc5300 would be good ram

[BUFF]

1:1 (the lowest CPU:RAM ratio that P35 chipset allows) is good when you are overclocking because unless you have spent a chunk of money on high end RAM it's usually the RAM that hits it's limit first on these systems so you need to drop that as low as possible.Typically you want to run your RAM as fast as possible though so if you are running stock you don't want to be running 1:1.

As for the E6600 the main advantage to that is it has a 9x multi which means that you only need to run 295fsb for 2.66GHz instead of 333fsb on the E6750 - basically for any core clock you can run a slower fsb as it has a higher multi available.

Best thing to do is to run your system spec. past the forum before you actually buy it but e.g. DDR2 800 potentially can handle an E6600 @3.6GHz (subject to a good chip, cooling etc.) without overclocking the RAM any. With an E6750 that would be 3.2GHz.

[aidanjt]

No no, forget about the RAM divider entirely, leave SPD to do it's job. The entire purpose of the northbridge is to uncouple the RAM from the CPU, which allows the CPU and RAM to talk to each other no matter what frequencies they run, as long as the northbridge can talk to both, everything will work together.

[cascade]

Havn't we all

heh i feared i was the only one!

Clearly then i was misunderstanding the whole thing, as this will be my first DDR2 AND Intel system, i think i'm a bit... competly lost I thought the 6600 / ddr6400 added up (divided up?) lol, but i get it now hopefully.
I'm so tempted to try it the more interesting way and go for 6750 / 6400, probably CorsairTwinX XMS2 specifically, for the giggles. I probably shouldnt, but still

Thanks again for your replies anywho, i imagine i'll post again asking more specifically about dividers etc in a few days time!

cheers

[Harkin]

As for the E6600 the main advantage to that is it has a 9x multi which means that you only need to run 295fsb for 2.66GHz instead of 333fsb on the E6750 - basically for any core clock you can run a slower fsb as it has a higher multi available.

.

But the E6750 has a multiplier of 9 aswell? and it is the G0 revision..

[cascade]

Ahh, good call BUFF. I'll do that 2m when i make some more choices.
@aidanjt Reading more about SPD as i type

many varying opinions already, i am intruiged! =-)

thx again!

[Tetras]

But the E6750 has a multiplier of 9 aswell? and it is the G0 revision..

Nope, E6750 multiplier is 8 (333 x 8 = 2664).

[Harkin]

Oh nevermind it is 8x multi, I have the E6850 so i thought it was the same.. woops