Originally posted by: deadseasquirrel
Originally posted by: chizow
Originally posted by: deadseasquirrel
Originally posted by: taltamir
it will be funny if the reviews sayings "free AA" just didn't realize they were CPU bound.... funny and sad
it will be funny if all the people claiming "CPU bound" just didn't realize there is a difference between CPU-limited and CPU-bound.... funny and sad
The only difference is semantics. GPU and CPU bottlenecks aren't mutually exclusive, you can be both simultaneously, you just won't know for sure until you lessen one or the other.
While I agree with you that CPU and GPU bottlenecks don't have to be mutually exclusive (nobody ever mentioned GPU bottlenecks), I disagree that the only difference between CPU-
limited and CPU-
bottlenecked is semantics. They are 2 different concepts in my mind:
CPU-limited-- a faster CPU will show an increase in FPS vs. a slower CPU matched with the same card in the same benchmark. i.e. the card's performance has been "limited" by the slower CPU. In my opinion, pretty much every single game and every single GPU are "cpu-limited" to an extent. A faster CPU will almost always result in better fps, even if just a small amount. It's that "amount" that determines whether one would be better off getting a faster CPU or not based on cost vs performance increase.
CPU-bottlenecked-- no FPS is seen when upgrading to a faster GPU. i.e. on a rig playing Oblivion at 1024x768 w/ an Athlon XP 1700+ and a 6600gt getting the same fps when the GPU is swapped for an 8800gt. You are now CPU-bottlenecked and a faster GPU won't help you. Again, just as an example... I don't know if that game with those components behave that way or not.
Here is an example. It's not a totally fair comparison because one benchmark is done with 2GB of ram and the other with 4GB. But, right now, it's one of the closest examples we can get to--
4870 at 4ghz, and
4870 at 3ghz.
This is UT3. At 3ghz, and at 1280x1024, you are
CPU-limited in this game. A 4ghz CPU with the same 4870 gives it a 60+% increase. BUT, you are not
CPU-bottlenecked at all at 3ghz because a faster GPU than the 4870 increases fps a lot.
And, in the same benchmark, just changing resolutions, we see the CPU-limitation disappear at 25x16 w/ a 3ghz CPU vs a 4ghz CPU with a single 4870. BUT, slap a second 4870 for CF and BAM, you have a CPU-limitation again, even at 25x16 because fps jumps up like 20%.
CPU-limitations and bottlenecks can vary across games and platforms. We see a lot of questions such as "will my E6600 hold back a 4870X2?". The answer is, of course, yes. Any CPU will be a limitation. But *how much* it will hold it back is the key. That varies game-to-game and resolution-to-resolution, all matched with varying CPUs. The honest answer to that question is that it's too difficult to answer such a generic question with narrow-focused reviews we have today.