DDR5 VS GDDR5

[00stevo]

Hello everyone,

 

So anyway im having a bit of a debate on another forum about gfx card memory.

 

I said ddr5 running @4ghz is no different from gddr5 running @4ghz.

 

He then hit me with an ambush of data which im going to copy/paste for you to dissect,here goes:

 

"Companies put the 'G' there because GDDR is different from DDR. Companies who don't put the G there are retarded.

 

GDDR is built for much higher bandwidth than DDR every will be, whilst using less power which in turn creates less heat.

 

DDR only has a 128 bit bus in dual channel mode (64bit x 2), or 192 bit for triple channel (64 x 3) whilst GDDR uses 4 - 8 channels creating a bus width of upto 512 bit (64 x 8). The higher bus width for GDDR allows it to transfer larger amounts of data in one clock cycle than DDR, and it'll be a very very long time before DDR needs a 512 bit bus.

 

There are a lot more differences but I can't be bothered expaining to someone who thinks the G is there because it looks 'cool'."

 

Now im not saying hes wrong but i stand by my statement until corrected by someone on here,cos i know you guys know what your on about.

 

Discuss!

[mattyamdfanboi]

well ddr5 doesnt actually exist persay as GDDR is Graphic memory.. and without the G term is used for normal PC ram.. and DDR5 for pcs doesnt exist yet.. hasnt even gone to DDR4 yet :/

 

so the debate is simple.. DDR5 doesnt exist and GDDR5 is Graphic Double Data Rate memory.. easy fix.

[red1776]

your buddy is correct. it is based on DDr3, but uses different write clocks . but he is right about the high bandwidth.

Edited July 9, 2011 by red1776

[mattyamdfanboi]

DDR4 come out this jan.. i correct myself.. but 5 is yet to exist lol

 

i should really read the entire topics before i reply to things lol

 

GDDR is much faster yes.. i think most pcs r at around 20-30gbps(intel triple chan) while most gfx these days r well over 100 with top end cards sitting at just under 200gbps for single gpus and well over 300 for dual setups..

Edited July 9, 2011 by mattyamdfanboi

[red1776]

I get what matt is saying...it;s like when someone claims that thier Ram is' dual channel'

[mattyamdfanboi]

dual chans r even less.. My current setup gives me about 15gps.. more than 10 times slower than one of my 580s.. which sit at 201gbs while over clocked.. each. lol but ur comparing a 128bit RAM setup to 384bit setup on the cards and more than twice the frequency...

[red1776]

no! LOL ...I meant the one that think the ram is 'dual channel'

 

here, this does a decent job of explaining the afforded bandwidth and clock/data transfer differences

 

GDDR5 (Graphics Double Data Rate, version 5) SGRAM is a type of high performance DRAM graphics card memory designed for computer applications requiring high bandwidth. Unlike its predecessor, GDDR4, GDDR5 is based on DDR3 SDRAM memory which has double the data lines compared to DDR2 SDRAM, but GDDR5 also has 8-bit wide prefetch buffers similar to GDDR4.

 

GDDR5 SGRAM conforms to the standards which were set out in the GDDR5 specification by the JEDEC. It uses an 8n-prefetch architecture and DDR interface to achieve high performance operation and can be configured to operate in ×32 mode or ×16 (clamshell) mode which is detected during device initialization. The GDDR5 interface transfers two 32-bit wide data words per write clock (WCK) cycle to/from the I/O pins. Corresponding to the 8n-prefetch, a single write or read access consists of a 256-bit wide two CK clock cycle data transfer at the internal memory core and eight corresponding 32-bit wide one-half WCK clock cycle data transfers at the I/O pins.

 

GDDR5 operates with two different clock types. A differential command clock (CK) as a reference for address and command inputs, and a forwarded differential write clock (WCK) as a reference for data reads and writes. Being more precise, the GDDR5 SGRAM uses two write clocks, each of them assigned to two bytes. The WCK runs at twice the CK frequency. Taking a GDDR5 with 5 Gbit/s data rate per pin as an example, the CK clock runs with 1.25 GHz and WCK with 2.5 GHz. The CK and WCK clocks will be aligned during the initialization and training sequence. This alignment allows read and write access with minimum latency.

 

A single 32-bit GDDR5 chip has about 67 signal pins and the rest are power and grounds in the 170 BGA package.

Edited July 9, 2011 by red1776

[00stevo]

So 'G' ddr5 is theoretically or actually faster than normal ddr5. Hmmm......

 

There was another guy who said he bought a gt240 with ddr5 because he assumed 'g' ddr5 was slower.I then said this: (copy/paste btw)

 

"

I must say you clearly dont know what your talking about.

How can the same card/s perform better just because one has the 'g' missing from the memory description?

 

Unless one is factory overclocked or has a higher memory or core frequency out of the box.

 

?"

 

Im actually puzzled myself here.I thought they only put the G there just cos it was on a gfx card.

[00stevo]

no! LOL ...I meant the one that think the ram is 'dual channel'

 

here, this does a decent job of explaining the afforded bandwidth and clock/data transfer differences

 

 

 

Hey +rep for that.

[mattyamdfanboi]

oh right lol yer nah the ram isnt dual channel lol its the "bus" it sits on that makes a difference.. AMD has 2 channels for the ram 64x2 and intel has 3 of them.. 64x3 gfx cards have . loads more and are at a higher frequency.. so its win for all!

 

and the G prefix doesnt make the ram any faster on a gfx card.. so u were right in saying that stevo

[red1776]

It almost sounds like you and your buddy,,,and Matt and I for that matter are arguing over different sides of the same fence

The older cards like this one are listed with and equipped with DDR2...I wonder if thats nor what he might be referring to.

 

http://www.newegg.com/Product/Product.aspx?Item=N82E16814134076

[00stevo]

oh right lol yer nah the ram isnt dual channel lol its the "bus" it sits on that makes a difference.. AMD has 2 channels for the ram 64x2 and intel has 3 of them.. 64x3 gfx cards have . loads more and are at a higher frequency.. so its win for all!

 

and the G prefix doesnt make the ram any faster on a gfx card.. so u were right in saying that stevo

 

Hey put that into a clearer paragraph so i can copy/paste it and shut him up!