Mobility 4870 512MB DDR3 vs. 1GB DDR5

Well, looking at getting a monster laptop and I have a Asus W90 in my eyes. Looks pretty sick except for something that I noticed a little too late but apparently the 4870x2 is only 512MB of DDR3 RAM...

Didnt think too much about it as the NotebookCheck site claims the 4870's are DDR5 1GB parts...however, it would seem that ONLY Alienware got these cards like this (dont know why NotebookCheck wouldnt correct this).

So basically my question is...how does the 1GB DDR5 vs. 512MB DDR3 compare? Like, I know the DDR5 would be faster, but are we talking like a WHOLE LOT faster or like a 5% increase over all? Also, I know that on desktop Crossfire setups the RAM is only used from one video card...is that true with laptop cards as well? Am I only running a 512MB 4870 on a 1080p screen? Or does it use the RAM from both cards for 1GB total? 512MB on a 1080p screen is going to suck...

 

Anywhere from 8-50% faster depending on the game and the settings, though it would be an average of 10% faster. Unfortunately, there are no Mobility 4870s with GDDR5.

 

You sure there are none with GDDR5?

Notebookcheck: AMD ATI Mobility Radeon HD 4870

Notebookcheck: AMD ATI Mobility Radeon HD 4870 X2 (Crossfire)

Both claimed to be 1GB GDDR5 parts. Also, the machines used in the benchmarks claim to be 1GB GDDR5 cards too, all Alienware.

Also, in the Asus W90, both cards are 512MB...will 1GB be available to use or is it still only 512MB total? Thats gonna put a major limit on game settings and resolutions...

 

It was a mistake, AW website used to show GDDR5 for 4870, but it was shipped with GDDR3, they probably had that GDDR5 4870 up as soon as AW announced it and didn't bother to correct it later on when proven false.

 

Oh really? So then officially for 100% sure no 1GB GDDR5 4870 exists then? I can understand the error on the specs list on Notebook but what about the people that did the benchmarks that claim to have the, and I quote, "Mobility Radeon HD 4870 X2 (550MHz), 1024MB (888MHz) GDDR5" in their "M17x (HD 4870x2)"? The review here:

Notebookcheck: Review Alienware M17x (i7/HD 4870 X2) Notebook

I quote "The HD 4870's GDDR5 VRAM has a total capacity of 1024 MBytes."

Hmmm...interesting...

 

Nevermind...looking at the pics saw this:



It would seem that it is only GDDR3...but it still says 1024MB...is that counting both cards 512MB or did the Alienware models have at least 1GB RAM after failing to do GDDR5?

EDIT: Also, it would appear that on AMD/ATi's website they claim the mobility 4850/4870 has GDDR5 RAM as well as GDDR3:

http://www.amd.com/US/PRODUCTS/NOTE...-HD-4000/HD-4850-4870/Pages/hd-4850-4870.aspx

"The 800 stream processors with GDDR5 or GDDR3 memory propel you deep into your gameplay with seamless frame rates at high resolutions"

 

Hey I own a crossfire setup on my desktop I loaded up gpuz for you, each card has 1gb and under gpuz it says 1gb ram + 2 gpus, so it seems the ram isnt added up.
Unless maybe the x2 is considered one card only. Hum...

 

Well, I know the 4870X2 is two GPUs on one card (desktop only), but in laptops 4870 x2 is just two 4870's...so unless the laptop parts can use the RAM from both GPUs the reviewer there must have something special...

 

Technically it uses the RAM from both GPUs, but the effective memory wouldn't be 2 gb (1gb + 1gb). It'll still be 1gb as the memory from the other GPU will just mirror what ever is on the primary GPU. So when they say 4870x2 1gb or 2gb, it's really just a selling point as the effective storage is half of those values. However, stream processing allows you to add up RAM through multiple GPUs running in sync.

Also, if you are still looking for a notebook with two cards using GDDR5, consider the Alienware M17x with dual Mobility Radeon 5870s. Each card uses 1gb of GDDR5. And don't be turned off by the 128 bit bus (kind of why they went with GDDR5), as it's currently the fastest GPU solution you can get.

 

Yeah, I know that the 128-bit is kinda offset by the DDR5 bandwidth.

So in either case, once and for all... there exists NO DDR5 Mobility 4870 nor is there a 1GB Mobility 4870 ONLY 512MB DDR3 4870...correct?

 

Well, after PMing a few people here with M17x Alienwares...it would appear that there are no GDDR5 Mobility 4870's despite what ATi's website says and many others...but there ARE 1GB GDDR3 4870's.

So...no GDDR5...but there are 1GB GDDR3 cards.

 

Not that the extra memory would really make much difference after 512MB.

 

Having two GPUs on 512MB is a bottleneck at high resolutions. I wouldn't go for it myself.

Heck, I wouldn't take one GPU with just 512MB.