What is scaling?

[nokturrduk84]

I asked on this forum if 7990 can work in crossfire and people said, yes but scaling would be terrible. So, I wonder what is scaling?
P.S. Sorry, if this question seems very noobish

[Sky Daddy]

Scaling is how much extra performance you get from crossfire. 

 

A 7990 in crossfire is essentially quad crossfire. Quad crossfire rarely scales efficiently and is very cost ineffective. Performance of 2 7990s isn't going that much more than 1 7990. (in most cases)

[delet my acc pls]

Scaling is how much extra performance you get from crossfire.

A 7990 in crossfire is essentially quad crossfire. Quad crossfire rarely scales efficiently and is very cost ineffective. Performance of 2 7990s isn't going that much more than 1 7990. (in most cases)

2 7990 is going to be like 3 7970 but stutter would mess things up so much you dont care about scaling

[exyia]

scaling is referring to the amount of performance you get per GPU

 

if you had one 7970 with 30fps

 

then added another 7970 and get 40fps

 

then that's considered very poor scaling - all that money to add a whole other GPU to get minimal performance

 

good scaling would be almost doubling fps for instance

 

people say two 7990's would scale poorly because that's 4 GPU's. The 4th GPU usually scales poorly regardless of card (though the GTX Titan has shown to scale well all the way to 4). amount of heat and power required to run the 2 extra GPU's from another 7990 is probably not going to net you enough fps for you to think it's worth it

[Vitalius]

To put it as simply as possible:

If you have 1 7970 and you get 60 average FPS, you would expect to 120 average FPS if you have 2 7970's (and so on with 3 and 4 7970's giving 180 and 240 average FPS respectively).

However, Crossfire is not that efficient (1:1 ratio). Scaling is talking about how well increasing the number of GPU's affects the average FPS you get.

Getting 1 7970 gives you 60 FPS, but getting a second one so you have 2 only gives you 80-90 FPS (just an example). That is what scaling is. 

Scaling for Crossfire beyond 1080p and dual GPU's is kinda bad. Usually at around 75% for the 2nd GPU, meaning instead of getting 60FPS, you would get 45, so you would have 105FPS. Again, just examples. 

And as you add more GPUs (a third and fourth one), the scaling gets worse and worse, like 50 and 25% kind of worse (respectively). 

[D3MON]

I will try and write it simply.

with 1 7970 you get 100% performance of a 7970..
with 2x 7970s you expect double the performance, 200% but infact you might get anywhere from 150%-180% but in this example well assume an 80% addition. (so 180%)
add a third and you might get another 60%..(240%)
and a fourth (which noone would reccomend with nvidia or amd) you might be lucky to get another 20% because for every card ou add the cards have to "talk" to each other more and the benefits begin to diminish rapidly.
amd for a while suffered stuttering because the cards (in corssfire) would often send frames at odd intervals which might give you 40% of a frame from card 1....then 10% from card 2...then the last 50% back to card one again. nvidia had it too but to a lesser extent and it was only brought to light when they were getting beaten in benchmarks
amds latest drivers have pretty much gotten rid of it, not completely but to the point its no longer a factor (source;pcper on the livestream)
bear in mind this is isnt an issue with single cards.
so yeah, the benefits diminish the more cards you add.
otherwise id love to have 4x 7990's in octafire in a 3960x build