Bond
L99: LIMIT BREAKER
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- 23 März 2010
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Heißt das, dass endlich das Marketing-Buzzword "latenzkritisches Physikgameplay" fallen gelassen wurde, wenn auch Cerny einräumt, dass Latenz nicht die Stärke von GDDR5 ist?
http://www.redgamingtech.com/ps4-vs-xbox-one-gddr5-vs-ddr3-latency/
But what about the actual latency of DDR3 vs GDDR5?
It’s worth remembering that if you do a little bit of Googling around, you can easily come across the specs of various GDDR5 memory. Hynix for example place PDF’s of their products freely available on the internet.
The latency on GDDR5 and DDR3 memory does vary some, but the typical CAS latency of most sticks of DDR3 is between 7 and 9 (see the earlier Tomshardware link for more information). GDDR5 RAM meanwhile is a typical latency of about 15. Once again, all of this depends on the make and models of the RAM.
So – there’s the answer right? Let’s say 8 CAS vs 15 CAS? No, it’s not. We have to remember that the speeds are for all intents and purposes – relative. If you take the CAS of both, and then multiply it by the clock speed – you get the ns of delay. CAS of 15/1.35 = 11ns.
I’ll save you the trouble and say that it’s between 10 – 12 for both DDR3 and GDDR5 varying heavily on the clock speed of either the DDR3 or GDDR5 AND in the timings they’ve chosen.
Also, take into account what Mark Cerny has said about GDDR5 latency:
“Latency in GDDR5 isn’t particularly higher than the latency in DDR3. On the GPU side… Of course, GPUs are designed to be extraordinarily latency tolerant so I can’t imagine that being much of a factor”.
What does it all mean?
It means that the Xbox One doesn’t have a latency advantage really with the DDR3 memory. It’ll have to try and rely on its ESRAM to make up for the lack of bandwidth which the DDR3 is of course, the culprit for. The X1′s ESRAM will have its work cut out, and from what the rumors are so far, the memory requires a lot of manual labour from the developers to get the most out of. It’s currently speculated that it’s being used for both a frame buffer and for tiled resources. However, much of its workings still remain a mystery.
Of course – in this article, we are not taking into account other aspects. These include the PS4′s extra graphical power, the extra compute work of the PS4 or its volatile bit. It’s also not taking into account API’s, drivers and code from developers.