about ddr2, ddr3, gdr2?

can anybody pls lecture me on the difference of the ddr2 ddr3 stuff etc.? their uses? their differences? thank you!

 

First, you have to distinguish between system memory and GPU memory. System memory is what the motherboard/chipset uses and can be either DDR2 or DDR3 (no notebook can use both). Only in ultraportables, does DDR3 have any benefit since it uses slightly less power. However, on most systems the power consumption difference is negligible. The performance difference is zero in all current systems since no CPU/chipset can even saturate the bandwidth of DDR2.

For GPUs, there are DDR2, DDR3, and GDDR3, with the former being the worst, and the latter being the best. The memory type here plays a lot bigger factor. For example a 9600M GT 512MB GDDR3 would outperform a 9600M GT 1GB DDR2. The memory amount only makes a difference in the highest end GPUs (256-bit bus). A simple rule of thumb (not absolute), is that GPUs can only effectively use memory that is up to double the bus width. So 64-bit cards only need 128MB, but most market these cards with 256MB, 512MB or 1GB, which is overkill since memory size isn't being used effectively and hence would yield no performance benefit. So don't pay more for that. I know I didn't really talk about the memory type much, but all you need to know about that for GPUs is in the first line of the paragraph.

 

Hi there mj_four.

As sgogeta said, there are two types of RAM. There is RAM that is what the CPU and overall the system uses to allocate memory. And there is VRAM which is Video RAM, used only by the GPU.

In the RAM world, DDR2 800MHz vs DDR3 1066MHz is no difference, and if any, this difference in performance in negligible in daily basis. (I think Photoshop would run better, but dont quote me on this, not sure). The only difference found here is that DDR3 is a tad less energy-hungry, so for those small devices that try to get the most out of the battery, DDR3 will give a very very slightly increase in battery.

NOTE: In the IGP or mGPU world, this is, integrated graphics, it is different. As IGPs use the RAM of the system, DDR2 vs DDR3 shows difference in performance, being DDR3 better in this case only. For example, NVIDIA 9400M G with DDR3 outperforms the same 9400M G with DDR2. But this is only for IGPs that use system memory, or RAM.

As for the GPU world, or dedicated graphics, VRAM plays an important role. There are currently, IIRC, 3 main types of memory: DDR2, GDDR3 and GDDR5. DDR2 is the worst of the 3, showing slower performance even in a similar card equipped with different memory, it is still used due to its low cost. GDDR3 is the most common ATM. Most GPUs nowadays use GDDR3 as VRAM, it is noticeably faster than DDR2 in GPUs. For example, as sgogeta said, the 9600M GT equipped with GDDR3 is much better than the same 9600M GT with DDR2. GDDR5 is the newest type of memory, used only IIRC in ATI highest-end GPUs, 4770HD and 48x0HD cards. This is the fastest memory, and theoretically speaking, it is double the fast as GDDR3. It is very rare, and I dont know if there are laptops already using them.

My advice is to let us know in the What Notebook Should I Buy? Forum the FAQ and we can help you that way. Most importantly, in the GPU world, you have to take in consideration bandwidth/interface, this is either 64bit, for entry level GPUs; 128bit for mainstream GPUs and 256bit for high-end GPUs.

Hope this was helpful. Any other question, feel free to ask, we are here to help!

 

i think this rule is obsolete now. hd4870 can use 1gb of video memory fine. even a gts250 1gb shows small improvement over the 512 version.

 

there is also ddr3. desktop hd4600/4500 can use ddr3 as a cheaper alternative to gddr3. it runs slightly slower. yet to see this in a laptop.
the new 40nm nvidia cards can do the same.

 

As it might be true that tianxia, so far AFAIK in the laptop world, I have not yet seen a GPU with DDR3. The closest using that are IGPs, that use system memory, been this DDR2 or DDR3 variants...

But thanks for pointing that out.

 

It still applies to most GPUs. The only ones that it doesn't apply to would be high end (256-bit) GPUs, which are more common in desktops. But notebooks, the majority of GPUs are still 64 or 128-bit.

 

i think it might still show a difference in high res with AA. but at those settings the game won't be playable anyway.

 

thank you very very much! the replies were very informative!!!

 

I agree. It was very well written and it's so useful. I wish I could know this much about computers. Thanks again for the information fellas!

 

No problem mj_four and Vinyard.
We members are here to help as much as we can (at least, I am here for that...lol) But seriously, feel free to ask anything you wish, someone will always be glad to help you.

Anything you want to ask me, shoot me a PM, and I reply ASAP.

Any more explanation that should be given on the DDRx matter?

 

DDR3 has twice the bandwidth of DDR2 at a given memory clockspeed. GDDR5 has twice the bandwidth of GDDR3 at a given memory clockspeed. With regards to graphics cards, it means that a card with a 256-bit bus and GDDR3 has the same bandwidth as a card with a 128-bit bus and GDDR5. The HD4770 and HD4850 have the same memory bandwidth. The same is true on the desktop with DDR2 and DDR3, but it doesn't really matter there. In today's computers, ram is really not a concern as it is extremely cheap for 4GB, which is all most users will ever need on their current systems, and memory bandwidth is in no way a limiting factor except for integrated graphics systems.

 

I have a quick question please

Can anyone enlighten me as to the differences between regular RAM and VRAM? I know one's optimized for graphics performance, but how exactly is it optimized? I figure if you can stick in DDR2 or DDR3(with little loss over GDDR3) in a GPU that the differences mustn't be that huge.

Also, I know that some GDDR memories are based off DDR memories. Like GDDR2 was based off DDR's architecture, but what of GDDR5? There isn't any DDR5 system memory so is that a completely new memory technology exclusive to graphics?

Thanks for your time

 

GDDR5 is the current graphics memory standard and it blows DDR3 out of the water. GDDR3 is comparable to DDR2 in chronology yet it still kills DDR3 which has twice the bandwidth of DDR2. Also the high end cards don't have compatibility for lower memory standards. The memory controller on the graphics chip must be built for all three standards, the standards are not directly compatible with each other. It is a lot more than just a couple of little tweaks if the much older GDDR3 has a large advantage over the newer DDR3.

GDDR2 is comparable to DDR, GDDR3 is comparable to DDR2, and GDDR5 is comparable to DDR3, at least chronologically. The numbers don't add up or have anything to do with each other actually. GDDR5 is simply the 5th technical spec/design of graphics card memory and DDR3 is simply the 3rd technical spec/design of DDR memory.

 

I know all that, but I'm wondering at the exact differences between DDR and GDD memory. If oyu can use DR memory in GPUs to substitute GDDR memory(at the cost of performanec), then they mustn't be apples and oranges either.

Yes I know that, but I was referring to similarities in architectural structure. GDDR2 was based off DDR's architecture to an extent IIRC.

 

All of the different specs are incompatible with each other. DDR2 and DDR3 are quite different, operating at different voltages, data rates, frequencies, and timings, yet there are chipsets that can be used for either one and other chipsets that can only be used for one or the other. If you add enough transistors to the memory controller, you can make it compatible with any type of DRAM. In the end it is just storing 1's and 0's in a specific order. Only cheap gpu's offer compatibility with multiple types of ram because the added transistors don't add much to the overall package and adds a lot of flexibility.

The specific general differences between desktop and video memory aren't readily quantifiable. In general graphics memory is more energy efficient, higher clocking, has more bandwidth for a given clockspeed, and costs a whole lot more.

GDDR3 is based on DDR2, but has twice the bandwidth per clock. GDDR4 is based on DDR2 also, as an improvement to GDDR3. GDDR5 is based on GDDR4. DDR3 is based on DDR2.

 

so is it right to feel that my laptop kinda sucks coz it has ddr2 in it?

 

No, not one bit.

 

is it like this?

laptop with gddr2 > laptop with ddr3 > my laptop with ddr2???

 

Wait, you mean for the video memory? GDDR2 has long been out of production and obsolete. If you have discrete graphics, GDDR5 > GDDR3 > DDR3 > DDR2 for the video memory and the computer's main memory doesn't matter.
If you have integrated graphics, DDR3 > DDR2 for the main memory.

 

thank you very much Trottel


+rep to you

 

I think Trottel left it very clear there.
Thanks!

 

there's GDDR4 too

 

just to complicate more stuff??
GDDR4, as exposed on a thread I started earlier today, never really caught up, and very few GPUs use it.