DDR2 & DDR3

smsmasters

smsmasters

smsmasters

Soldato
Joined
26 Aug 2004
Posts
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Let's say I have my e6600 @ 3.6ghz (400FSB x 9)

With DDR2
FSB: 400MHz
RAM: 400MHz(800MHz)?

Would DDR3 be:
FSB: 400MHZ
RAM: 800MHZ(1600MHz)?

So DDR3 is x2 as fast per clock than DDR2 or have I got it wrong?
 
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I'm pretty sure you're wrong. All three type of DDR would be at 800MHz with a 400MHz clock, it's just that DDR3 runs at higher clock speeds than DDR2 which, in turn, runs at higher clock speeds than DDR. Obviously not the only difference but it's the one that's relevent....
 
DDR1 was simply 200x2=400mhz commonly used PC3200

DDR2 is 100x2x2=400mhz (not many used 400mhz DDR2 so it would be more common for 200x2x2=800mhz (PC6400 we mostly use today).

DDR3, I have not took much interest in yet.
 
Snapshot is correct.

It's not the "2" in "DDR2" that signifies that the speed is doubled, it's the "DDR" abbreviation which is "Double Data Rate".
 
Ofcoarse it is the DDR part, but the way it gets to the final end user clock is as above and its not same for DDR1 and DDR2, unsure on DDR3 TBH.

Thats why I threw in the old uncommon DDR2 @ 400mhz so it was compairable to DDR1 PC3200 @ 400mhz
 
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Yeah, sorry, mine was just a very simplifed explanation to explain the user than the number on the end of the "DDR" isn't the reason it's mulitplied by two, think we just posted at the same time so my post wasn't attempting to show you as being wrong, as I'm sure you are correct in what you are saying.
 
smsmasters said:
So at 400MHz FSB, DDR2 would be at 800MHz, what would DDR3 be?
Click to expand...

It's EXACTLY the same. The primary differences between DDR2 and DDR3 are the signaling voltages and the fact that DDR3 can hit higher frequencies. The way you are asking the question seems like a 4 cylinder car and an 8 cylinder car both at 100kph speed; which is going faster? They are the same speed but, the 8 cylinder car has a higher speed potential.
 
helmutcheese said:
DDR1 was simply 200x2=400mhz commonly used PC3200

DDR2 is 100x2x2=400mhz (not many used 400mhz DDR2 so it would be more common for 200x2x2=800mhz (PC6400 we mostly use today).

DDR3, I have not took much interest in yet.
Click to expand...


eh?

DDR2 PC6400 runs at an actual 400Mhz, 800Mhz effective compared to DDR.

where are you getting this 200x2x2 from?
 
Out the Air where do you think ?

Google it, and see the DDR2 diff from DDR1 (not talking speed) cause DDR2 at 800mhz is same speed as DDR3 at 800mhz as pointed out above.
 
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DDR 800 = 400 MHz memory clock, 400MHz I/O clock, 800MT/s

DDR2 800 = 200MHz memory clock, 400MHz I/O clock, 800MT/s

DDR3 800 = 100MHz memory clock, 400MHz I/O clock, 800MT/s

All types of memory provide the same bandwidth at the same rating, but the higher the ddr type, the higher latency they have because of the slower memory clock. DDR3 just allows the memory clock to be kept lower, so the I/O clock can be increased more to get higher bandwith. Chips seem limited to a memory clock of little more than 200MHz. Though cpus don't need this much bandwidth anyway, which is why dual channel mode doesn't make a difference to performance. Lower latency gives better performance than higher bandwidth.
 
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So what's the differerence between memory clock and I/O clock?

I was only aware of one frequency. So your saying each module operates with two frequencies?

So when increasing the modules frequency your are only increasing the I/O clock?
 
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