Basics of LGA775/Core2 Duo/DDR2 Systems?

[Big.Wayne]

Hi,

I'm interested to get up to speed with the latest kit. I've built a lot of INTEL systems in the past (Socket7/Slot 1/FCPGA/Socket478) but I've never used a LGA775 or DDR-2 system before so I wanna get a few things right.

I understand that the (quad-pumped) FSB has now been raised from 200MHz (800MHz-FSB) to 266MHz (1066MHz-FSB) but am not sure which DDR2 memory runs at this speed?

Are people getting the best results from just upping their FSB and running the memory 1:1 sync or does it have much of an impact if you use a divider on the memory (async)?.

Are you able to adjust the Core2 Duo's multiplier in anyway? You never really were able to do this in the past with an INTEL CPU but I think I read that you can now adjust the multiplier downwards?

Also what is it like fitting a LGA775 CPU for the first time?

Think thats it for now, if you feel you can add any basic info for someone who is new to LGA775/DDR-2/Core2 Duo it would be much appreciated!

 

[Jokester]

DDR2 runs at double data rate, but with the combination of memory dividers can run at effectively any old speed compared to the actual FSB. Where RAM is rated as 6400, it runs on a 400MHz bus. To run RAM on a 266MHz bus (givin the quad pumped speed of 1066MHz) you just need 4200 rated RAM.

Core2Duo multi's are selectable down to x6 (depending on BIOS) but locked upwards from default.

Most people are running their RAM 1:1 when overclocking on the 975x chipset as it seems flaky on other dividers.

Fitting wise you just drop it in the socket and close the retetion clip.

Jokester

 

[Big.Wayne]

DDR2 runs at double data rate

I thought regular DDR memory did that? do you mean it runs at double the rate of DDR

Haha I'me even more confused now Jokester

Can you give me an example? I'm not getting this DDR2 thing at all

 

[Cob]

Nah DDR2 runs at double date rate just like DDR.

Eg- If your fsb is at 300Mhz and you use the 1:1 divider, your ram will run at 600Mhz.

It's just named DDR2 because it's the next generation and can run at far faster speeds than DDR.

 

[Big.Wayne]

Ok Cob cool!,

can you tell me what the stock speed of your E6600 is (and Multi) then tell me what adjustments you made to your FSB to hit 3.6Ghz?

I'm trying to work out what is the good memory to be looking for. If the stock FSB is 266MHz (x4= 1066MHz) I'm guessing you want your memory to reach as high as possible (like 400MHz+), What is the FSB limit to these newer mobo's then?

Is there a nice list somewhere where I can see the stock values of these Core2 Chips? (GHz and multi's) as I was looking at getting the cheapest one possible (e6300?) and am aware its probably got a low value multi and I will need to hit a high FSB meaning:

Cheap CPU = Expensive Mobo + Expensive Ram
Expensive CPU = Bargain Mobo + Bargain Ram

Looking at getting CPU + Mobo + RAM for testing purposes, not sure which option above would work out best?

 

[Cob]

Ok Cob cool!,

can you tell me what the stock speed of your E6600 is (and Multi) then tell me what adjustments you made to your FSB to hit 3.6Ghz?

Stock speed of my e6600 is 266x9. My chip craps out at 3.6Ghz so i have a choice of 400x9 or 450x8. I run it at 450x8 as it's slightly faster in benchmarks due to the higher FSB and RAM speed.

I'm trying to work out what is the good memory to be looking for. If the stock FSB is 266MHz (x4= 1066MHz) I'm guessing you want your memory to reach as high as possible (like 400MHz+), What is the FSB limit to these newer mobo's then?

The C2D mobos are capable of 500+, depending on your luck. PC6400 (DDR2-800) is what you want for overclocking a C2D, preferably CAS4 as it has a lot more chance of reaching higher speeds than the CAS5 stuff.

Is there a nice list somewhere where I can see the stock values of these Core2 Chips? (GHz and multi's) as I was looking at getting the cheapest one possible (e6300?) and am aware its probably got a low value multi and I will need to hit a high FSB meaning:

Cheap CPU = Expensive Mobo + Expensive Ram
Expensive CPU = Bargain Mobo + Bargain Ram

e6300 is 266x7, e6400 is 266x8, e6600 is 266x9 and the e6700 is 266x10. The X6800 is 266x11 but has a fully unlocked multiplier.

A cheap cpu + cheapish board and expensive RAM is often the best bet eg- e6300 + Gigabyte DS3 + PC6400 C4

That combination should get an e6300 to over 3Ghz, possibly a lot further depending on your luck.

 

[Jokester]

What FSB speeds a mobo will do depends on the CPU and the chipset.

965 chipset boards are particualrly good at overclocking the Allendale cores, typically exceeding 500MHz in some cases. 975X boards will typically do 400-420MHz for Conroe cores though some can do upto 450 with some luck. The new Nvidia 680 chipsets are getting at least 450, not sure what to expect top end, maybe 500+ with luck.

Jokester

 

[Big.Wayne]

e6300 is 266x7, e6400 is 266x8, e6600 is 266x9 and the e6700 is 266x10. The X6800 is 266x11 but has a fully unlocked multiplier

Thanks Cob, I appreciate you taking the time to write that!

965 chipset boards are particualrly good at overclocking the Allendale cores, typically exceeding 500MHz in some cases. 975X boards will typically do 400-420MHz for Conroe cores though some can do upto 450 with some luck.

Thanks Jokester, thing I don't understand is why the cheaper chipset is capable of hitting higher FSB's? Why is anyone using a 975x chipset then?

One other thing I wanted to confirm, I read somewhere that the CD2 works better the higher the memory bandwidth is, to the extent that in some examples the system was faster with the memory set to a higher divider? i.e The memory is running at a higher speed than the FSB (async!)?

Apart from that I think I understand it all now, except this new DDR2 memory speeds, I know all the older DDR ratings off by heart

PC2100 - DDR266 (FSB 133MHz)
PC2700 - DDR333 (FSB 166MHz)
PC3200 - DDR400 (FSB 200MHz)
PC3500 - DDR433 (FSB 217MHz)
PC3700 - DDR466 (FSB 233MHz)
PC4000 - DDR500 (FSB 250MHz)

etc. . .

So is this list below correct?

PC2-4200 - DDR533 (FSB 266MHz)
PC2-5300 - DDR667 (FSB 333MHz)
PC2-6400 - DDR800 (FSB 400MHz)
PC2-7200 - DDR850 (FSB 450MHz)
PC2-8000 - DDR1000 (FSB 500MHz)


As far as CPU's go the CD2 e6700 seems kinda handy with it x10 multi

 

[Jokester]

Yeah that list is right, The E6600 is the sweatspot in my opinion for the Conroes as you'll be able to hit 3.6GHz on a 400MHz FSB on air if you're lucky.

The main benefit of the 975x chipset is Crossfire support something I think the 965 doesn't support.

Testing with the new Nvidia 680i chipset appears to show that there is no significant penalty in running the RAM async. The faster you can get your RAM running the better. In my experience (P5W) 975X boards can get flakey if you run more than 1:1 though as they struggle with RAM speeds over 800MHz.

Jokester

 

[Cob]

Some of the P965 boards will do Crossfire eg- the DS4 will, but only at x4 on the second pci-e slot or summit like that.

Thanks Jokester, thing I don't understand is why the cheaper chipset is capable of hitting higher FSB's? Why is anyone using a 975x chipset then?

The P975x is an updated version of Intels flagship desktop P975 chipset that has been around for a while and was originally designed for P4's.
The P965 is a brand new chipset specially designed for the Core 2 Duos. The fact it is specially designed for C2Ds probably goes some way to explaining why it's 'better' for overclocking than the patched P975x.

 

[silversurfer]

ddr2 ram will generally overclock to the next rating, 533 > 667 etc

You really need the bandwidth when multi tasking but I dont think running the memory faster then the fsb gives great gains otherwise