SLI in rebirth

[fenix67]

Hi guys not sure this has been brought up but will rebirth support SLI.

[elexis]

Someone needs to look up how SLI works...

[CBJ]

Games don't support (or indeed not support) SLI. The whole point of SLI and Crossfire is that they are supposed to be completely transparent to applications that use the graphics card(s). It's possible for a game to benefit to a lesser or greater degree from an SLI or Crossfire setup, but it's up to NVIDIA and AMD to make sure their drivers support games' use of standard DirectX calls, not the other way around.

As to the question of whether X Rebirth benefits from SLI, I'd say the answer is that it would benefit somewhat more from it than previous X series games. That's not saying all that much, though, since previous X series games were almost entirely CPU bound and throwing more graphics card power at them rarely had much effect at all.

[BugMeister]

Someone needs to look up how SLI works...

some might argue that AMD needs to do more research as well..


- but, that does sound promising, CBJ
- thanks for the "tid-bit"..

[Chris0132]

Some games do have issues with SLI but yeah, it's not something the developer has to take into account, it's supposed to do it by driver magic on the GPU manufacturer's end.

Though given my experience with SLI, it mostly tends to overheat and crash a lot.

[Cycrow]

yeah cramming 2 power hungry and hot cards next to each other doesn't seem like a good idea

its not so bad if its watercooled thou

[Scoob]

yeah cramming 2 power hungry and hot cards next to each other doesn't seem like a good idea

its not so bad if its watercooled thou

I don't know about that, it heats our smallest bedroom during the winter months for "free"

Scoob.

[dougeye]

certain game engines don't get on well with SLI, the engine used for Spacemarine, darksiders, darksiders 2 runs like a snail through sli, luckily these games are not taxing enough to stress a single card of reasonable power. currently playing darksiders 2 now

[ajax34i]

SLI doesn't have to be watercooled, but you can't rely on the manufacturer's fan settings either, because they are set for "quiet" operation. At the very minimum, download an app like MSI Afterburner of EVGA Precision to manually set the fans to higher speeds.

Not that FrozenCPU doesn't have cool stuff.

[BugMeister]

yeah cramming 2 power hungry and hot cards next to each other doesn't seem like a good idea

its not so bad if its watercooled thou

I don't know about that, it heats our smallest bedroom during the winter months for "free"

Scoob.

- like it..!!

[Hrodeth]

Someone needs to look up how SLI works...

some might argue that AMD needs to do more research as well..


- but, that does sound promising, CBJ
- thanks for the "tid-bit"..

You stuck in 2006? AMD has been yonks ahead of Nvidia for a while now, and a much more affordable price as well.

[fenix67]

Games don't support (or indeed not support) SLI. The whole point of SLI and Crossfire is that they are supposed to be completely transparent to applications that use the graphics card(s). It's possible for a game to benefit to a lesser or greater degree from an SLI or Crossfire setup, but it's up to NVIDIA and AMD to make sure their drivers support games' use of standard DirectX calls, not the other way around.

As to the question of whether X Rebirth benefits from SLI, I'd say the answer is that it would benefit somewhat more from it than previous X series games. That's not saying all that much, though, since previous X series games were almost entirely CPU bound and throwing more graphics card power at them rarely had much effect at all.

Cheers thanks for the info CBJ im sticking to a single card for now anyway, as ive got a gtx 770 anyway so it should be fine. I was just curious, as some games dont benifit from SLI, as was said. I was just asking in case, in the future i add a second card.

Someone needs to look up how SLI works...

I do know mate, just phrased it wrong. i was just asking if rebirth will benifit from SLI, as some games dont.

[boxleitnerb]

At least in the case of SLI, Nvidia provides developers with certain heuristics as far as I know. These are guidelines, if you will, and if a dev doesn't stick to them, SLI support can be broken. There are instances where a simple profile update is not enough - a game patch is needed as well. You cannot put the responsibility on the IHV alone.

In any case, SLI/CF can show significant benefit, even in CPU bound games. For example I could play X3 with 8xSGSSAA which would not have been possible with just one GPU. A CPU bottleneck would then (often) have become a GPU bottleneck, resulting in low fps. With SLI, that was no problem at all.

[ajax34i]

X3AP, taking control of Flak turrets and aiming them so the gun barrels are visible, then shooting them, makes my game slow down to 2 FPS as the flames gush out of the barrels. I'd bet SLI helps with that, somewhat. Maybe 4 FPS.

[Shush]

Games don't support (or indeed not support) SLI. The whole point of SLI and Crossfire is that they are supposed to be completely transparent to applications that use the graphics card(s). It's possible for a game to benefit to a lesser or greater degree from an SLI or Crossfire setup, but it's up to NVIDIA and AMD to make sure their drivers support games' use of standard DirectX calls, not the other way around.

In a perfect world this would be 100% true, but as we all know this fictitious perfect world doesn't exist. It's exactly this pre-conception about SLI, (that it magically should just work with 0% effort from the developer), that causes games to have poor or inconsistent performance.

As rendering techniques advance and the use of asynchronous queries, (event queries and occlusion queries) and feedback techniques using render targets, fbo's and stream buffers become more widespread, the chance of SLI performing poorly because of inter-GPU synchronisation issues and increased inter GPU communications needs increases dramatically. A simple way of understanding it is; every GPU resource is duplicated n times with n extra video cards in SLI, anything that causes these resources to change or get out of synchronisation forces the resources to be updated n times for each video card's memory.

What this means in practise is that unless you are writing the most naïve and simple of games it's prudent not to stick your head in the sand and assume that the SLI gods will take care of everything.

Here's an excellent NVidia white paper that explains why good SLI performance is also the responsibility of the developer.

https://developer.nvidia.com/sli-best-practices

[CBJ]

Shush, what you say refers to getting benefit from SLI or Crossfire. My original post was about support for SLI, i.e. the game actually running on a system with multiple cards in SLI, not about whether it can make the most of such a system. The OP has since agreed that the question wasn't phrased quite right, which makes a difference.

Having said that, it's not surprising that NVIDIA would like other people to do the work. To put it in your terms, they are living in a "fictitious perfect world" in which individual game developers can afford to spend a lot of time tuning for a technology used by a small fraction of gamers.

The reality lies somewhere between the two, of course. It's up to NVIDIA and AMD to make it work transparently, and it's up to game developers not to do anything too silly.

[betc]

Very much liking what im hearing from CBJ...

SLI will give more benefits than previous X games
Potential for 3D support

time to figure out how to do Frame Sequential 3D so the tiny HUD writing in X3 is visible [/list]

[dougeye]

will NVIDIA physics as an example be of any benefit with Rebirth? if the game is not incredibly taxing graphically will this leave the abilily to set your secondry GPU dedicated to physics freeing up a little processing power?? if you know what I mean.... lol

[Chris0132]

The problem there is that unless AMD has an equivalent to nvidia's physics, you can't really do much with it, because half the playerbase can't use it.

[BigBANGtheory]

That is not entirely true as Nvidia PhysX can be run through a CPU thread it doesn't have to run on Nvidia hardware. I'd image though there would be licensing costs for Egosoft I doubt very much its a free solution.