[Editorial] Something very interesting was given to me recently. A slide from a PS4 presentation which showed the total bandwidth of the PS4 GPU. The Bandwidth in question is claimed by most PR documents to be around 176GB/s as most of you know, but it turns out that the actual bandwidth is somewhere around 140GB/s and drops even more when heavy CPU utilization occurs. While the latter isn’t particularly shocking, the same can’t be said for the actual bandwidth limit. Before I begin, let me state that I have dropped Sony PR an email and will update this editorial as soon as I get a response.
PS4 GPU has an Effective Bandwidth of 120 to 140 GB/s, Not 176 GB/s As Previously Reported
The slide comes from a technical presentation of the Sony PS4 system and as such, it must be treated with the utmost caution. However, from what I can see, if there is one thing you cannot deny, its that the effective/usable/actual (whatever you want to call it) bandwidth available to the Pitcairn GPU of the PS4 is 120GB/s to 140GB/s. By this I mean the actual bandwidth available to the developers to play with. The problem is, this is something that cant really happen. Not unless the memory clock we know is incorrect too. Confused? let me explain. The bandwidth and the effective memory clock are linked. this is how the equation goes. Lets assume a memory clock 5500 Mhz and a bus of 256Bits. This is how the equation will go [5500 Mhz * 256 Bits = 1408000] then [1408000/(8*1000) = 176]. As you can see, a memory clock of 5.5Ghz and 256 bit bus has to result in 176 GB/s bandwidth. Unless, one of the other variables are incorrect, or the basic premise is flawed.