globalisateur said:
- PS3 used GDDR3 @22GB/s (for GPU) - PS4 uses GDDR5 @176GB/s (APU) - PS5 will probably use GDDR6 @1000-1408GB/s (APU) DDR4 is too slow compared to GDDR6 exactly the way DDR3 is too slow compared to GDDR5. |
We have no idea how GDDR6 will perform.
As for Ram in general, it's amazing how much of a focus it's had lately, when the majority of the world didn't care when GDDR5 released 6 years ago.
As for speeds... Considering you can already set-up DDR3 to have more bandwidth than GDDR5... It kinda' makes it all moot.
DDR3 running at 3000mhz (Like some Samsung modules can) on a 512bit bus will net you 192Gb/s of bandwidth, more than the PS4 and majority of PC GDDR5 graphics cards sold.
It's estimated that DDR4 could hit around 4266mhz, on a 512bit bus that would net you 278Gb/s of bandwidth.
To put that into perspective, the Radeon 290X, AMD's fastest graphics processor has 320Gb/s of bandwidth on a 512bit GDDR5 bus, granted they could eek more out of that by clocking the memory higher, for instance if the 290X's memory was clocked at the same rate as the Radeon 7970 (1500mhz x4) but retained the 512bit bus it would have 384Gb/s of bandwidth instead of only 320Gb/s.
If it used the same clocks as Cape Verde (1625mhz) then you're looking at 416Gb/s of bandwidth and there is probably more room to move.
What it all ultimatly comes down to is... Cost.
In order for DDR3/4 and other "PC System DRAM" to achieve similar bandwidths as GDDR5... You need to have either twice the memory bus bit or twice the clocks, if you go with the former option then you need twice as many memory modules and a much more complex memory controller to drive it all.
In order to have a cost advantage over GDDR, you need orders of magnitude cheaper memory chips to make up for the added complexity which scales of economy can provide.
And because consoles are cost sensitive devices that are made cheaply, it usually doesn't make much economical sense to go with a more complex higher performing design.
By extension depending on the price of GDDR6, the consoles may actually end up going with DDR4 or even with GDDR5, even if they stick with GDDR5 it wouldn't be all that difficult to double the bandwidth at a minimum.
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