And racing games are typically not very demanding to render, so there's more possibility to spend budget on RT without impacting the rest of the presentation.
Lockhart would also be rendering much lower resolution, which will reduce the calculations needed. Even if it's only 4TF as rumored, number of rays should be about 1/3rd of XSX. If resolution is only 1/4 (1080p vs. 2160p), there shouldn't be much problem. This rough number does seem to indicate lowered RT quality if Lockhart renders at 1440p, or if XSX is rendering below full 4K.
It's confirmed. The way Microsoft promoted their RT performance is by saying XSX can do 380 billion intersections per second. This number is amount of TMUs times clockspeed. (TMU is Texture Mapping Unit, of which there are 4 per CU.) This gives an exact figure of 379.6; doing the same calculation for PS5 gives a value of 321.1. That's 15% lower, the exact same gap as general compute...which makes sense, since it's dependent on the same two things, amount of CUs and clock.
In other words, if a PS5 game is 15% lower resolution, then it should have the same quality of RT. Or, XSX could have 15% better RT, but then the two games would run at the same resolution. (In general, logical terms only, of course; real results will differ slightly from game to game.)
The GPU operates on data stored in its local caches. When those calculations are done, the results are sent back to RAM and new source data is loaded from there. When the GPU clockspeed is high, calculations finish faster so you need to refill the RAM more often. But GPU clockspeed doesn't apply to RAM, which has its own invariant bandwidth. That means the windows where RAM will accept requests are farther apart, compared to the amount of math you're doing.
This is why people with technical know-how think the RAM bandwidth may be a limiting factor for both PS5 and XSX performance. The way both platforms might not be bandwidth-starved is if they can keep as much data in the local caches as possible, reducing trips to RAM. But also, AMD has worked to reduce bandwidth needs for the same amount of work by changing the architecture.
This may also be ameliorated by the fact that PS5 is likely to have more L2 cache per CU than XSX.
Please stop this. Mr. Battaglia has been part of our community for years prior to his employment at DF, as a level-headed and reasonable contributor. Of course he may well have personal biases, but the public statements he makes are grounded in expertise and knowledge, with an obvious intent to be informative, not divisive. You've heard him mostly talking about XSX because Microsoft has simply given more detail about the tech inside their machine. (And perhaps also because through DirectX more of it will apply to PC, which has always been his platform of choice.)
Thanks
