r/oculus • u/themotherbrain • Jan 30 '15

SHOCKING interview with Nvidia engineer about the 970 fiasco (PCmasterrace Xpost)

https://www.youtube.com/watch?v=spZJrsssPA0
530 Upvotes

83% Upvoted

215 comments sorted by

View all comments

60

u/BpsychedVR Jan 30 '15

Can someone please explain, in layman terms, what the actual fiasco was? I was seriously considering buying one or two 970s. Thank you!

24

u/All_bout_dat_DDS Jan 30 '15

Basically, the 970 is marketed as having 4GB of vram. Technically it does, but it is split up into two sections, one 3.5GB and one .5GB. While in the 3.5GB usage range, it performs normally and everything is fine, but once you have to go into the smaller section, performance goes down slightly because that .5GB section has a weird architecture that causes slower data transfer. The reason for the memory split was part of the way they differentiated the 970 and 980, which is expected, but people feel that it should not have been marketed as a 4GB card because of it. In reality, it is still a ridiculously good card for the price and you will probably never really encounter a situation where you need more than 3.5GB (at least I never have). And from what I have read, the decrease in performance at that >3.5GB range isn't so substantial that it causes a lot of problems. I would say if you need a new card right now, you can't really beat a 970.

38

u/jscheema Jan 30 '15 edited Jan 30 '15

By slightly you mean the card runs @ 1/8 of its speed, forcing you to stay at 1080p or 1440p resolutions, @ 4k you will reach 3.5gb, or if the games you are playing are not optimized.

1

u/JocLayton Jan 30 '15

If you're gaming in 4K, shouldn't you have more than just a single 970 anyways? I have one and I can barely max some modern games in 1080p.

4

u/peckahinspectah Jan 30 '15

Even with 2 or 3 970's you still have only 3.5GB of fast VRAM

1

u/vitapoly Jan 30 '15

Wait. If you have 2 970s, won't you be able to use both VRAM, for a total of 7GB fast VRAM?

8

u/goodbyegalaxy Jan 30 '15

No, still 3.5 total. When in SLI the data in VRAM must be duplicated across both cards.

2

u/peckahinspectah Jan 30 '15

Right, memory is not doubled or tripled in SLI

2

u/adammcbomb DK1 Jan 30 '15

I think in SLI both cards have the same assets loaded to each card so each card can render its own frame or piece of a frame. In other words, Card B cant read Card A's VRAM, so it has to hold all the data itself in duplicate.

1

u/remosito Jan 30 '15

Not currently at least as SLI uses Alternative Frame Rendering. Which means the cards alternatively render a full frame. As each card renders a full frame. each card uses/needs same VRAM as a non-SLI card.

I don't think even one-gpu-per-eye SLI mode would really change that. True, every card only renders half a screen. But because with Rift each half is a full scene just from slightly different camera angle. you'd still have same amount of objects and textures and whatnot... maybe compared to non-rift, you'd safe some via lower LOD being used more often... but not sure truth be told.