Suggestion for the 1C Devs

[flyingblind]

The OP dose have a point. I have a mid-range card with 1GB memory and at least wish I had got a 2GB version. The best option for me would be to buy a second matching card if only I could be sure that would work properly. Do I waste the first card and go for a better single GPU or do I risk wasting more, albeit a smaller amount of money on a SLI setup?

[Stublerone]

Originally Posted by flyingblind

The OP dose have a point. I have a mid-range card with 1GB memory and at least wish I had got a 2GB version. The best option for me would be to buy a second matching card if only I could be sure that would work properly. Do I waste the first card and go for a better single GPU or do I risk wasting more, albeit a smaller amount of money on a SLI setup?

Take into consideration, that 2 x1gb cards won't help. It is not 2 gb!!!!! It is still 1gb in sli, so your memory is way to low. Even a 2gb card will have problems in maxed setting and 1080p resolution, as the game will consume more than 2gb. My hd7970 is consuming up to 2,7 gb !!!! So even a sli with 2 x 2gb cannot help that much. So, 2 gb is the lowest memory, u should have to run it with some higher details, but still with stutters, if you are unlucky.

[Blackdog_kt]

Originally Posted by flyingblind

The OP dose have a point. I have a mid-range card with 1GB memory and at least wish I had got a 2GB version. The best option for me would be to buy a second matching card if only I could be sure that would work properly. Do I waste the first card and go for a better single GPU or do I risk wasting more, albeit a smaller amount of money on a SLI setup?

Sorry to be the bearer of bad news, but SLI doesn't increase your available video RAM.

I'm not exactly sure why, but i think that if cards use split frame rendering they render half of each frame, but they need to store the entire frame in each card's memory.

When they render alternate frames (eg, card 1 renders frame 250 and card 2 renders frame 251) the same holds, because each card has its RAM filled with an entire frame.

You do have double the video RAM but you also use double, so there is no gain in available memory.

[6BL Bird-Dog]

From experiance I got various results with different card combo`s single and X-Fire.
1x AMD Saphire Toxic 5870 Oc, poor frame rates and micro studders,had to use medium settings .
2x AMD Saphire Toxic 5870 Oc,best ever performance when the early patch release enabled X-Fire,Max settings, good high frame rates and only the microstudders low.Ruined when a small patch was bought out within hours because of graphics anomolys with Nvidia systems.
1xXFX HD 7970 Black Edition,Improvement on single 5870, but running at Very High in game settings made little difference ,frame rates improved slightly.
2xXFX HD 7970 Black Edition,with both last Alpa and Beta patches more or less the same as a single XFX HD 7970 Black Edition performance slightly improved at highest settings.
I tested the same cards and setups on the rig in my sig and did compare performance with RoF and iL2 1946 ,the latter of which does not have X-Fire support.
In Rise of Flight as I Improved my Gpu hardware I was able to increases my quality settings with also an increase in FPS .The 2x AMD Saphire Toxic 5870 Oc performance was slghtly slower than a single XFX HD 7970 Black Edition.
2xXFX HD 7970 Black Edition runs fluidly with all settings at max with the exception of AntAliasing which Inever run above 2x as it murders the fps in ROF.
iL2 1946 ran maxed out on all combinations ,seamlessly on 2xXFX HD 7970 Black Edition, with the Average FPS limited to 60mhz(my native screen res),but max frames are almost always over 1000fps.
The Clod dev team hit the sweet spot once for me on X-fire but have never unfortunately got close since.
In Cliffs of Dover`s present state apart from increasing in game video quality settings performance wise X-Fire is not functioning in anyway near to the Early X-Fire patch release which on my system was awesome compared to any patches before or after,the textures looked much better then too if a little bit too bright.

[SKUD]

Originally Posted by Blackdog_kt

Sorry to be the bearer of bad news, but SLI doesn't increase your available video RAM.

I'm not exactly sure why, but i think that if cards use split frame rendering they render half of each frame, but they need to store the entire frame in each card's memory.

When they render alternate frames (eg, card 1 renders frame 250 and card 2 renders frame 251) the same holds, because each card has its RAM filled with an entire frame.

You do have double the video RAM but you also use double, so there is no gain in available memory.

So let me make sure I have this straight. Nvidia wasted $$ putting an extra 1.5 GB of DDR5 on my 590 in full knowledge that it would never be used ?? Now they did it again with the 690 throwing away 2GB of VRAM because SLI can never use the VRAM from both cards. Those silly guys. Thanks for the tip.

[Blackdog_kt]

Originally Posted by SKUD

So let me make sure I have this straight. Nvidia wasted $$ putting an extra 1.5 GB of DDR5 on my 590 in full knowledge that it would never be used ?? Now they did it again with the 690 throwing away 2GB of VRAM because SLI can never use the VRAM from both cards. Those silly guys. Thanks for the tip.

Well, google is your friend.

EVGA forums, scroll down to 9th reply by user HeavyHemi: http://www.evga.com/forums/tm.aspx?m=1421266&mpage=1
Also note that the prevailing advice in that thread if you want to really crank up the resolution while also keeping the detail settings high, is to get a single card with the highest amount of RAM you can afford. So it's not only modern flight sims that work this way (RoF also had a lot of problems with SLI early on, but i can't comment on its current state because i don't have it on my PC), it seems to be a more widespread trend in other games too.

Tom's Hardware SLI and Crossfire FAQs:
http://www.tomshardware.co.uk/forum/...crossfire-faqs

Incidentally, in the above link you can also find this little gem:

Do SLI or CrossFire always improve performance ?
Not always.
There are some games that don't benefit from MultiGPU technology(or require a patch in order to utilize it).
For example,Flight simulator X doesn't benefit from either SLI or CrossFire.
Another example is StarCraft2 which barely benefits from more than 1 card

So FSX, a flight sim that was very demanding in graphics and CPU until hardware could could catch up with it, doesn't benefit from it. Sounds very familiar. Also note that Starcraft2 is a blockbuster AAA title.

Both of them are made by companies that could throw tons of cash on the issue. FSX is getting old and microsoft is more concerned with selling DLCs for its new MS Flight, but this wasn't always the case. Yet, they didn't fix it.
Also, SC2 is at its peak and its only part one of a trilogy, with a highly competitive multiplayer scene (think professional gamers who get paid like footbal players to take part in tournaments, etc) and the company behind it (Blizzard) has the enormous world of warcraft MMO cash-cow at its disposal and raving mad fans who buy everything they release (eg, the recent Diablo III).

If these guys can't do it or won't spend the time and money to, then the only reason i can think of is that SLI/Xfire setups are a bit too particular in terms of how you code your game in order to work correctly. It seems like the game has to be written around it and since it's a somewhat rigid and not so evolving technology (the cards evolve, but the technologies that pair them not so much), maybe it's not worth the compromises in other parts of the engine?

I'm just thinking out loud here, but the whole thing seems to completely debunk the entire "two cards = double the performance" logic. I've been ordering my PC components separately since forever and the only people i routinely see going for SLI setups are those that primarily focus on action/shooter games (simpler engines, small maps, elementary game mechanics, so all the PC has to do really is to run good graphics at a high frame rate).

The bottom line is, just because we might have some extra money to burn on a PC build doesn't mean we should go for the most expensive options. They might be kind of specialised in what they work well with.

[He111]

DRAT! you mean I bought an extra GTX 5980 for nothing!?

But wait, I'm future proof when game developers advance and develop for 2+ Gpus .. but WAIT!

Hopefully Rome2 will take advantage of multiple cores and GPUs?

.

[SKUD]

Originally Posted by Blackdog_kt

Well, google is your friend.

EVGA forums, scroll down to 9th reply by user HeavyHemi: http://www.evga.com/forums/tm.aspx?m=1421266&mpage=1
Also note that the prevailing advice in that thread if you want to really crank up the resolution while also keeping the detail settings high, is to get a single card with the highest amount of RAM you can afford. So it's not only modern flight sims that work this way (RoF also had a lot of problems with SLI early on, but i can't comment on its current state because i don't have it on my PC), it seems to be a more widespread trend in other games too.

Tom's Hardware SLI and Crossfire FAQs:
http://www.tomshardware.co.uk/forum/...crossfire-faqs

Incidentally, in the above link you can also find this little gem:


So FSX, a flight sim that was very demanding in graphics and CPU until hardware could could catch up with it, doesn't benefit from it. Sounds very familiar. Also note that Starcraft2 is a blockbuster AAA title.

Both of them are made by companies that could throw tons of cash on the issue. FSX is getting old and microsoft is more concerned with selling DLCs for its new MS Flight, but this wasn't always the case. Yet, they didn't fix it.
Also, SC2 is at its peak and its only part one of a trilogy, with a highly competitive multiplayer scene (think professional gamers who get paid like footbal players to take part in tournaments, etc) and the company behind it (Blizzard) has the enormous world of warcraft MMO cash-cow at its disposal and raving mad fans who buy everything they release (eg, the recent Diablo III).

If these guys can't do it or won't spend the time and money to, then the only reason i can think of is that SLI/Xfire setups are a bit too particular in terms of how you code your game in order to work correctly. It seems like the game has to be written around it and since it's a somewhat rigid and not so evolving technology (the cards evolve, but the technologies that pair them not so much), maybe it's not worth the compromises in other parts of the engine?

I'm just thinking out loud here, but the whole thing seems to completely debunk the entire "two cards = double the performance" logic. I've been ordering my PC components separately since forever and the only people i routinely see going for SLI setups are those that primarily focus on action/shooter games (simpler engines, small maps, elementary game mechanics, so all the PC has to do really is to run good graphics at a high frame rate).

The bottom line is, just because we might have some extra money to burn on a PC build doesn't mean we should go for the most expensive options. They might be kind of specialised in what they work well with.

Clearly my 590 is not using all the 3GB of VRAM it has in COD because I can directly compare it to my 3GB 580. So my question again is why would Nvidia build a card that can't use half of its VRAM under any circumstances? If this is the case then a 590/690 is nothing more than a 580/680 with a bonus space heater attached.

Never mind... my friend Google found this Gem.

"Originally Posted by CousinVin
I think i understand that putting two 3gb cards still only limits you to 3gb of usable vram.. right? If that is wrong please correct me.
You are correct.
Quote:
Now my confusion comes in with the GTX 590. It is labeled as a 3gb card, but from the assumption above, and considering that it is 1.5gb per core, is it really only 1.5 gb usable vram?
It's marketing. Joe Average can't tell the difference between total memory and dedicated memory."

So anyone looking at the 690 beware.

[Royraiden]

Its amazing that a feature that almost any current game has and a feature that was promised to be introduced/fixed more than a year ago is still not present in a sim that has so many problems performance wise and Im amazed that some guys here seem to encourage the devs to forget about a feature that could be really helpful if implemented correctly.When I bought my second video card it made a world of difference, specially on ROF, other more common titles were running a lot better to say the least.I never experienced micro stuttering or any problem related to the use of crossfire.Gpu's prices go down really quick so buying a second card to make a crossfire/sli setup is a lot cheaper than buying a single monster card.People of this community need to see things from a wider angle, having this feature could only make positive changes but on the other hand not having it as you can see is a negative thing in my opinion. By the way Im only running one card now so dont assume that I wrote this just because I had a dual gpu setup.I would be happy if multi gpu support got improved even if I cant benefit from it right now.

[Blackdog_kt]

Originally Posted by SKUD

Clearly my 590 is not using all the 3GB of VRAM it has in COD because I can directly compare it to my 3GB 580. So my question again is why would Nvidia build a card that can't use half of its VRAM under any circumstances? If this is the case then a 590/690 is nothing more than a 580/680 with a bonus space heater attached.

Never mind... my friend Google found this Gem.

"Originally Posted by CousinVin
I think i understand that putting two 3gb cards still only limits you to 3gb of usable vram.. right? If that is wrong please correct me.
You are correct.
Quote:
Now my confusion comes in with the GTX 590. It is labeled as a 3gb card, but from the assumption above, and considering that it is 1.5gb per core, is it really only 1.5 gb usable vram?
It's marketing. Joe Average can't tell the difference between total memory and dedicated memory."

So anyone looking at the 690 beware.

Yup, that's how it works. Each GPU needs its own RAM regardless of whether you have two cards with a GPU on each, or a single card with two GPUs on it (like the 690 i think). Also, each RAM has to store the entire frame before it's displayed, regardless of the SLI method used (either card 1 renders frame 1 and card 2 renders frame 2, or each card renders half of each frame).

So, when you see a single card with a dual GPU specifying 3GB of RAM on the box, what it means is 3GB divided equally among the two GPUs and mirrored for each frame -> 1.5Gb of effectively usable video RAM.

If your preferred games are heavy on textures and have long viewing distances (more textures need to be loaded per frame) it's better to go for a single 3GB card or two separate cards with 3GB each. View distance is probably the main reason that players of action and shooter games get great performance with SLI. Their view distance is nothing compared to a flight sim so this RAM issue is not so perceptible.

In the above 3GB example, to load the textures that the single card or the two-card SLI setup can, an single-card SLI setup like the 690 would have to have a total of 6GB of RAM (3 for each card).

I hope i didn't make any typos to make this confusing (it's a bit late at the moment and i'm sleepy) and that it sufficiently explains the limitations of the architecture in terms of RAM usage. Cheers