PDA

View Full Version : DDR vs. GDDR Memories


Anusha
12-09-2006, 06:24 PM
Source: hardwaresecrets.com

RAM memory is also used on video cards to make the video memory circuit. Until recently the video memory used the exact same technology as the system RAM memory that is installed on the motherboard. High-end video cards, however, needed memory chips faster than the ones used on the PC. So the manufacturers decided to go for DDR2 and DDR3 technologies.

DDR2 and DDR3 memories used on video card have different characteristics than the DDR2 and DDR3 memories used on the PC – especially the voltage. That’s the reason they are called GDDR2 and GDDR3 (the “G” comes from “Graphics”).

In our DDR2 Memory Tutorial we explained the differences between DDR and DDR2 memories. As we mentioned there, one of the main differences is the voltage: while DDR works at 2.5 V, DDR2 works at 1.8 V. This leads to a lower power consumption and less heat.

GDDR2 memories continue to work at 2.5 V. Since they run at higher clock rates compared to DDR memories, they generate more heat. This is the reason why only a few video cards used GDDR2 memories – only GeForce FX 5700 Ultra and GeForce FX 5800 Ultra used this kind of memory. Shortly after GeForce FX 5700 Ultra was released many video card manufacturers released a GeForce FX 5700 Ultra using GDDR3 memories, maybe to lower the heat and power consumption effects.

http://img224.imageshack.us/img224/5931/gddriioq9.jpg
GDDR2

http://img224.imageshack.us/img224/6547/gddriiiwr6.jpg
GDDR3

GDDR3 memories can work at 2.0 V (Samsung chips) or at 1.8 V (chips from other manufacturers), solving the heat problem. This is the reason why this kind of memory is used by high-end video cards.

DDR3 memories are not released to PCs yet, but they will probably work at 1.5 V, being different from GDDR3 memories.

Physically speaking, both GDDR2 and GDDR3 use BGA (Ball Grid Array) packaging, the same used by DDR2 memories, as you can see on the figures. It is impossible to visually detect whether a memory chip is GDDR2 or GDDR3. The solution is to search on Google or on the manufacturer’s website for its part number (K4N26323AE on Figure 1 and K4J55323QF on Figure 2, for example).

shanX
12-09-2006, 07:24 PM
But I think DDR3 (1066mhz) and GDDR4 available now.

Anusha
12-09-2006, 07:32 PM
DDR3 is not released yet. It will be released with the Intel Bearlake chipset, which will boost the Core 2 Duo's FSB to 1333MHz up from 1066MHz. The new stream of Core 2 Duo's will be called Core 2 Duo Refresh - up to 3GHz (333x9) I believe.

GDDR4 is available, but only on X1950XTX video card. Not even Geforce 8800GTX has them. Geforce 8800GTX has only GDDR3 at 1.8GHz (2x900MHz).

shanX
12-09-2006, 07:43 PM
Isnt 1066MHz DDR3?

Anusha
12-09-2006, 07:53 PM
Isnt 1066MHz DDR3?

No. DDR2-1200 is also available.