DDR3 - Thought I had this worked out

stoofa

stoofa

stoofa

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OK, I thought I had the DDR3 requirements all sorted out in my head - instead I think I've just managed to confuse myself.
Right....
Taking the 3 most popular DDR3 speeds:

1066 - So this is for 133MHz memory clock, 533MHz FSB
1333 - So this is for 166MHz memory clock, 667MHz FSB
1600 - So this is for 200MHz memory clock, 800MHz FSB

So assuming a Core 2 Duo CPU with a FSB of 1333MHz.
This is still actually a quad pumped 333MHz FSB (If I remember correctly).
So for stock speeds, 1333MHz DDR3 would be required (333MHz FSB x2).

So assuming a Core 2 Duo CPU with a FSB of 1600Mhz,
This is still actually a quad pumped 400MHz FSB (Remembering...).
So for stock speeds, 1600MHz DDR3 would be required.

Now this looks fine on paper, however I believe this is actually all wrong and I'm using maths for DDR2 and not DDR3 which is worked out differently.
Could somebody just confirm for me at stock speeds:

CPU FSB 1066Mhz = ???? DDR3
CPU FSB 1333MHz = ???? DDR3
CPU FSB 1600MHz = ???? DDR3

Thanks.
 
Everytime it gets talked about it ends up with a fight so I ain't going to go down that route of info again so will tell you what I think you need to know in layman terms.


You have 2 choices with DDR3, lets say you bought 2000mhz Memory.

1) Run it at 1000mhz if you have overclocked your Quad Pumped FSB to 2000mhz.

2) Run it at 2000mhz in line with your overclocked Quad Pumped FSB at 2000mhz


Most class #1 as 1:1, but all NForce Mobos call that Linked+Sync'd, they class #2 as 1:1.

If your going for the Option #1 then there is little point in buying a DDR3 set up till your Quad Pumped FSB can overclock to 2500-2600mhz, meaning you need 1250-1300mhz Memory and that's about the limit of most DDR2 1250 even OC'd.
 
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helmutcheese said:
Everytime it gets talked about it ends up with a fight so I ain't going to go down that route of info again so will tell you what I think you need to know in layman terms.


You have 2 choices with DDR3, lets say you bought 2000mhz Memory.

1) Run it at 1000mhz(500Mhz) if you have overclocked your Quad Pumped FSB to 2000mhz.

2) Run it at 2000mhz(1Ghz) in line with your overclocked Quad Pumped FSB at 2000mhz


Most class #1 as 1:1, but all NForce Mobos call that Linked+Sync'd, they class #2 as 1:1.

If your going for the Option #1 then there is little point in buying a DDR3 set up till your Quad Pumped FSB can overclock to 2500-2600mhz, meaning you need 1250-1300mhz Memory and that's about the limit of most DDR2 1250 even OC'd.
Click to expand...
 
See that's why I don't like replying in a DDR3 thread as nobody seems to know how it works or count its clocks.

Why quote my info ?, I do know how it works and why it is now used. :confused:.

The above is true I said but you could benefit from Memory Bandwidth in some Benches and APP's, IMO its not worth it for that alone but it still remains it will give gains or there would be no DDR3 Mobos or Modules.

If someone really wants a new Mobo, likes one they find but finds out its DDR3 only and cant afford DDR3 then go for it.

You trying to say you cannot run a stock E8500 is a Intel Chipset Mobo with its FSB at 1333mhz and have the Memory at the same 1333mhz ?.

Same for overclocked to 1600mhz or 2000mhz.
 
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DDR3 1333Mhz(666.5 x 2)would overclock the CPU's FSB to 666.5Mhz if running 1:1 on any other board apart from an nForce one.

Now are you able to overclock the CPU's FSB upto 800Mhz(DDR3 1600) or 1Ghz(DDR3 2000) or course you can't(yet) so there is no need for it yet.


yadda yadda....
 
You can OC the FSB to a end result of 2000mhz and have a Memory at a end result of 2000mhz.

That is what DDR3 is for, it don't matter a monkeys if its not classed as 1:1 by Intel or such.

Many in here do not even have there rigs at 1:1, there is 1 peep in the OCUK Store's comments section running a Intel Rig with his FSB at 1333 and his DDR2 Memory at 1333mhz.

Take that up with Nvidia or such.

Every CPU and Mobo sold is marked by the QP FSB same as Memory is sold by its DDR speed. (argued this before and scanned photos of all Boxes).

To say a E8600 has a FSB of 333mhz is not exactly the way Intel want it as they class it as a 1333mhz FSB CPU.

The new Mobo lying here next to me has 1600mhz FSB marked on the box, not 400mhz FSB. ;)

I have reluctantly gave the OP an answer not needing another boring debate about DDR3 and how it does/doesn't work and if its needed or not. ;)
 
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They MARKET it at 1333Mhz, Not class it as 1333Mhz, there is a difference :)

A quad pumped FSB is just that a frequency multiplied by four. So it's not technically a 1333Mhz FSB it's a 333Mhz x 4 FSB. But to keep things simple and to make things sound faster than they really are they use the equivalent frequency of a single channel FSB(for people who don't really care about the details)
 
You need file a lawsuit against INTEL and all Memory makers then m8, if you are not happy with their marketing.

I'm basically fed up answering same Q's all the time anyhow (there is 3 dupe topics in the Memory section multiple times per week), esp when it ends up a debate not even with the OP.

I answer as I do not like see someone stuck but think enough is enough TBH.
 
so by that theory...

e.g

Q6600 = 1066mhz DDR3 memory
QX9650 = 1333mhz DDR3 memory
QX775 = 1600mhz DDR3 memory

So whats the 2000mhz memory for?
 
Reality|Bites said:
Yup you are a brick wall. You know the truth but won't admit it to yourself :)
Click to expand...

No, you seem to be saying I'm wrong as are Intel/AMD and all Memory Vendors.

Deal with them legally if you are so against it instead of doing my nut in m8.

Your input does not help the op in the slightness.
 
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ConTRo13R said:
so by that theory...

e.g

Q6600 = 1066mhz DDR3 memory
QX9650 = 1333mhz DDR3 memory
QX775 = 1600mhz DDR3 memory

So whats the 2000mhz memory for?
Click to expand...

Yes the DDR3 Memory is to let your DDR Speed match your Intels CPU's FSB Quad Pumped Speed.

1333FSB through to 1600FSB Officially and 2000FSB Overclocked.

Most peeps would not use DDR3 1066 same as they would not have used DDR2 400 (DDR1 400 officially covered this), and most would have 1st used DDR2 Memory at DDR2 533.

I'm talking in Speeds instead of Bandwidth names, hope you still understand.
 
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The question is,
Is there any real world noticeable difference in running your E8400 which has 333fsb
with a memory @ 400mhz (PC6400) or 533mhz (pc8500), ofcourse taking the stock timings.

I personally would try to run my MEM/CPU as close to 1:1 as possible and it thats not possible then I will try to run my memory at the best mhz/timing ratio.
 
Doesnt matter if you have DDR, DDR2, or DDR3, they are all double datarate memory types, and the modules available for PC's are 64bits wide.

The CPU is also running on a 64bit wide bus, but its quad data rate.

So with single channel DDR/2/3 you would need 533mhz (1066ddr) memory to match the bandwidth of a Core2 Duo on a 266mhz (1066quad pumped) bus. This is 1:1

However as high speed memory was expensive intel switched to dual channel 128bit memory interfaces. The processor remains at 64bit. The effect of this is that 266mhz (ddr533) is a 1:1 bandwidth match with a 1066 Quadpumped FSB.

If you overclock the heck out of a processor, and get 500mhz (2000FSB), then all you need is dual channel 500mhz (1000DDR/2/3) to achieve a 1:1 bandwidth match. A single channel setup would need 1000mhz DDR.

2000mhz DDR2/3 is a complete waste of time for a 500mhz cpu bus, as the bus between the motherboard and the cpu would be saturated when the ram is only 50% bandwidth saturated. Although you would make some small gains in latency though.

Nehalem/bloomfield raises some interesting questions though, as it will have an integrated memory controller. As this removes the bottleneck between the CPU and motherboard, it will be able to utilise higher speed memory. Who knows what maximum speeds intel will certify to though, we already know they are intending to move to tripple channel (192bit) memory interface on Bloomfield, so they may be aiming relatively low on the memory clockspeeds.

I've always found best performance at the 1:1 bandwidth point, so speed depends on the width of the memory interface on the motherboard. As most are 128bit dual channel 333FSB = DDR2 5300! at stock speed. Anything faster than DDR2@667mhz is for overclocking. And for an older Conroe with a 266FSB anything over DDR2 PC4200 is for overclocking.

Anyone who try's to sell DDR3 2000, is just selling by numbers, no different to a double glazing salesman trying to sell his 20mm airgap over a 12mm airgap (efficiency difference about 0.5%)
 
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Basically I'm thinking thus:

At the back-end of the year we will be seeing new CPUs/Chipsets from Intel.
These will be based on DDR3.
At the moment I'm already in the wonderful world of DDR3, but as I cascade my old machine down to my wife I will need to make more purchases.

So when the new Intel CPUs make an appearance at the end of the year we'll be looking at FSB or 1333 or 1600.
If I want to run at a 1:1 memory ratio I would need DDR3-1333 or DDR-1600 memory.
If I owned DDR3-1333 memory and had a CPU with a FSB of 1600 I'm assuming I'd simply have to run the memory at a lower ratio.
 
sounds about right yes!

so if i buy a 790i with some DDR3-1333mhz and a QX9450 i'd have an out of the box 1:1 ratio
 
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