GDDR3 vs GDDR5 and 512mb vs 1gb

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beamed24

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I am building a system currently, and have been wondering what the benefits of these are.

gddr3 and gddr5 - it seems to me that I have no real clue what the difference is :)

getting a 1gb card vs a 512mb card - A bunch of deals at the egg right now for 4850s with 512mb for ~115

Id like to get a 4850 or 4870, and assume getting a 1gb version would be better. I run a lot of CS3, Painter X, Maya, and lightwave. And I do love me some good video games. From my understanding, a 1gb card is better.

I want to buy a single card right now, with plans to add a second for CF setup.

My current setup that i am building is:
MSI P45 Diamond MOBO
PC Power and Cooling SILENCER 750W QUAD S75CF
Intel E8400
8gb Corsair DDR3 (4x2gb)
Antec 900 case
2 Lite-on Burners
1 WD 500gb HD
1 Seagate 1Tb HD

Not sure if i will use xp 64bit (most likely) or Vista 64bit
I have each of them from SChool!!(Says woohoo, Free OS's)

What do you guys and gals think??? I am so tempted to buy a 4850 512mb, but would also love to get a 4870 1gb for the same price as two 4850's and wait a year and add another 4870 1gb
 

Avenger_K

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What resolution are you going to be playing your games at?

From what I've seen in benchmarks, the GDDR5 makes little or no difference in gaming performance. However, there are occasions when 1GB of memory can make a difference. I'd probably say 4870 1GB.
 
If you`re going to install 8Gb of memory you will need to use a 64-bit OS, a 32 bit OS can only `see` a total of 4Gb, so the extra 4Gb will simply not be recognised or used.
GDDR5 is faster than GDDR3 and is the main reason the HD4870 is faster than the HD4850, otherwise the two cards are much the same.
If your monitor is less than 16x10 there`s no real reason to go for a 1 Gb card, the extra memory is really only used at higher resoloutions.
 

Avenger_K

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Good point on the 64-bit operating system. However, the HD 4870 is faster than the 4850 not because of its memory, but because of the increased clock speeds (750MHz core vs. 625MHz core). The GDDR5 does nothing (or very little) performance-wise, which I believe is due to its increased latency over GDDR3.




Ahh yes, I forgot to include that in my last post. +1
 


Actually, the GDDR5 is quite significant - graphics cards love bandwidth, and high bandwidth memory is a very good thing on higher end cards. The 4850 reacts better to memory overclocks than core overclocks - why do you think this is?

Also, note that Nvidia is using massive bus widths (512 bit) on their top end cards - do you really think they would do this (along with the massive costs associated with it) if there weren't significant gains to be had from large memory bandwidth?

Basically, I would take a 4870 512MB over a 4850 1GB because of this (and the higher clocks), and the 4870 1GB is fastest, though it only really has an advantage at higher resolutions >1680x1050.
 

beamed24

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I was thinking of using a quad core processor, but most programs do not really use the 4 cores yet. The e8400 i already have and can be OC'd really well. The whole system will be watercooled, which should help for good OCing.

I want to run dual 24's at 19xx x 1200, and gaming isnt the most important (although it is in the back of my head :)).

so from what i am reading, a 4870 with 512 mb is going to be better than a 4850 with 1gb?

I do want to eventually CF the cards, and the card hierarchy chart says that CF'd 4850s are a little better than a single 4870.

Then there is the whole issue of the 4830 CF'd, which after reading here and other places that that card shines in the OC'ing department
 

Hari Seldon

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GDDR5 vs GDDR3 discussions rarely, if ever, mention the sizes of these cards. I have a mobo with a GDDR3 card in one of the two PCI-E slots. I'd like to upgrade the card before making this computer the "2nd" computer. Are all GDDR5 cards the same dimensions as GDDR3 cards?
 
No, the memory chips themselves are the same size so that has no effect on the size of the card, its just that GDDR5 was only used on the higher end cards which are larger than average. The new ATI 5xxx series has GDDR5 on many of the cards, and if you are looking for a smaller card something like the 5670 would probably fit the bill for you.
 
I agree with the general consensus that you should go with the 4870 over the 4850. I had a 4850 prior to getting my current 5830 and I occasionally mess around with rendering, i.e. AutoCAD (it has nothing to do with what I do, I just like messing around with it) and the difference between the 2 is night and day. A friend has a 4870 and also has AutoCAD- there is a noticeable difference as well between the two. I think you'd be happy with the 4870 or perhaps a 5xxx series card if you want to spend the money.
 

ares1214

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they both offer quite a bit higher bandwidth. to my knowledge, gddr5 offers 2x the bandwidth of gddr3, so a gddr5 256 bit bus= a gddr3 512 bit bus. the difference between ddr2 and ddr3 is some irregular number i think.
 

sabot00

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I would get 512MB of GDDR5 over 1GB of GDDR3 (as long as bus speed and everything else is the same).
First and foremost choose GDDR5, then if it allows choose 1GB (512MB might be better if you have a 32-bit OS).
 

ares1214

Splendid
agreed. basically, heres how it works. if you have a 32 bit os, get the 512 mb one. for dual 19x12, get the 1 gig one. to be honest, id just stop debating, spend a bit extra, and get a 5750 or 5770.
 

Hari Seldon

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Good advice. I've researched the user reviews and I'm deciding between the 4870, the 5750 or 5770 you've suggested.

I'm just wondering now about the dimensions of these cards you've recommended, because I want to be sure they'll fit and I'm having a hard time finding this info.

Are the lengths of these cards you recommend the same as my current GDDR3 card?

Are all the GDDR3 and GDDR5 cards the same length and that's why they don't bother printing this info so we dim ones can find it? :)

 
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