Chirag's Planet

Difference between DDR and DDR2

1. What is the difference between DDR and DDR2?

On the physical side, DDR has a 184-pin DIMM interface and DDR2 has 240.

DDR2 runs cooler and has generally slower timings but is a lot faster than DDR in the end. DDR2 is capable of holding more ram on one DIMM.

2.) Does DDR2 do more work per cycle? And Does AMD Support DDR2 Ram?

AMD doesn't support DDR2 as the A64's built-in RAM controllers would have to be upgraded therefore making them incompatible with all the current motherboards out there which really wouldn't be worth AMD and the board manufacturers' time.

The differences:

• DDr1=184pin DIMM and DDR2=240pin DIMM.
• DDR2 has much higher bandwidth and chip density/# of chips per DIMM, allowing more ram to be effectively used (also the reason why it's best to go for 1-2gb of DDR2) at a higher speed, but at the expense of latency.
• On the other hand, DDR1 runs at lower speeds but much tighter timings

It is difficult to differentiate a DDR2 from a DDR motherboard just by looking at it.  Inserting a DDR2 DIMM into a DDR motherboard could damage the module, the motherboard, or both. To prevent such damage, the simplest process is to align the memory module and the socket, and visually check that the module “key” aligns perfectly with the socket key. You may have to turn over the memory module as the memory module direction may misalign even compatible socket and module keys.

3. What latencies will standard DDR2 DIMMs support?

JEDEC DDR2 specifications define standard DDR2 CAS Latencies of 3, 4, and 5:

– 400 MHz DDR2: CAS 3 (3-3-3)

– 533 MHz DDR2: CAS 4 (4-4-4)

– 667 MHz DDR2: CAS 5 (5-5-5)

4.: What latencies do Kingston HyperX DDR2 modules support?

HyperX memory modules support enhanced CAS Latencies:

– 533 MHz PC4300 DDR2: CAS 3 (3-3-3)

– 675 MHz PC5400 DDR2: CAS 4 (4-4-4)