HD 7850 1GB Crossfire questions

[Imake&IsellSoap]

I was wondering if anyone could answer a few questions because I do not really know how crossfire works precisely. I have looked at some benchmarks at various sites and it seems it is very difficult to max out the VRAM on a single 1gb version of the HD7850 on 1080p resolution, or at least it would only require some small sacrifices to get it under and such a game would probably be running on to low a frame-rate for it to even to playable on the card anyway.

However, I am wondering, does adding another 1gb version of the card in crossfire give you an effect 2gb VRAM, so theoretically crossfire-ing this card would allow you even to play Battlefield 3 on 2,560 x 1,600, 4xAA, maximum settings, or would both cards be bottlenecked as they are only 1gb?

Furthermore, especially if the latter would indeed cause problems, would crossfire on these cards at 1080p on a intensive game (say Battlefield 3 maxed) cause a the VRAM to bottleneck the card/s at all given the bump from about 40 fps to ~75 and the increase workload the cards would have.

I hope I am being clear, It makes sense in my head but maybe not on paper. I basically just do not know how VRAM works in crossfire.

 

[Hardeep294]

Hey, welcome to the forums In answer to your question, VRAM stays the same over crossfire (and SLI)

 

[NightSt@lk3r]

Both cards will require a copy of the data in their own respective VRAM, so you will still only have 1GB of usable VRAM.

 

[Rusty0611]

As above.

I wouldn't crossfire 2 7850 1GB's.

 

[psychodil]

1gb isn't enough now for even a single 1080p screen. Really strange that amd released a 1gb version, its a bit pointless as the 2gb version is only about £10 more.

 

[Imake&IsellSoap]

Both cards will require a copy of the data in their own respective VRAM, so you will still only have 1GB of usable VRAM.

Ah OK thank you guys, I still wish they could do a 1.25 or 1.5 version of the card like the 570 and 580, but I think VRAM will be OK at 1080p at max settings on future games (maybe a few tweaks as time rolls on) for a long time.

 

[Nuclear Fusion]

As mentioned above, I wouldn't crossfire two 7850 1GB cards. The Vram would definitely cause some bottlenecks with crossfire- it might even with a single card ion some games, though I'm not sure on that one.

 

[Imake&IsellSoap]

1gb isn't enough now for even a single 1080p screen. Really strange that amd released a 1gb version, its a bit pointless as the 2gb version is only about £10 more.

Can you show me some examples of the fps dropping because of the 1gb vram on games at 1080p, it seems like it is very difficualt to do.

 

[Rusty0611]

Can you show me some examples of the fps dropping because of the 1gb vram on games at 1080p, it seems like it is very difficualt to do.

Run BF3 on the Ultra pre-set and enjoy

 

[spixelspixel]

I saw some reviews of the 7850 1gb card and absolutely no difference at 1920x1080 on the most demanding games with a single card.

If you already have a 7850 1gb and want to crossfire I say go for it.. and let us know the results.

1gb didn't stop 560 ti SLI from being awesome.

 

[Imake&IsellSoap]

Run BF3 on the Ultra pre-set and enjoy

I am not sure if it is against forum rules to link it, but I have seen a test by bit-tech which demonstrates that the hd6950, almost identical in performance, gets the same fps with the 1gb and 2gb versions on this game at 1080p, everything maxed.

 

[Defy Belief]

Reviews show practically no difference in Vram stats for 1080p, people just think they need it and that 1gb isn't enough, i'd still get 2gb just in case though but so far they still hold well.

 

[psychodil]

Can you show me some examples of the fps dropping because of the 1gb vram on games at 1080p, it seems like it is very difficualt to do.

http://forums.overclockers.co.uk/showthread.php?t=18344284

If you want to add MSAA (which you would certainly have the GPU grunt to do) you would be getting more buttraped with only 1GB.

 

[Imake&IsellSoap]

http://forums.overclockers.co.uk/showthread.php?t=18344284

If you want to add MSAA (which you would certainly have the GPU grunt to do) you would be getting more buttraped with only 1GB.

That is what I was looking for, definitely seems that the card is being restricted by its 1gb VRAM. It is a shame I cannot find the exact ram usage. I wonder if turning aero off (or using a program like gamebooster) would reign back a bit VRAM.

 

[psychodil]

That is what I was looking for, definitely seems that the card is being restricted by its 1gb VRAM. It is a shame I cannot find the exact ram usage. I wonder if turning aero off (or using a program like gamebooster) would reign back a bit VRAM.

It would gain you up to 150Mb, but still might not be enough for BF3 and upcoming games, and certainly not enough for MSAA. Far better to find the little extra money than to have regrets a few months down the road.

 

[Rusty0611]

I think 1080p max settings uses about 1350-1500 (factoring out the VRAM caching)

 

[passey89]

i'll fraps my sli 570's 1.25gb running out of vram tmoz for u. does it on high eith 4 x msaa and hbao on.

 

[humbug]

I think 1080p max settings uses about 1350-1500 (factoring out the VRAM caching)

Ya, that's about what i'm using at Ultra Preset, but BF3 will use whatever is available (with in reason) 1GB is not good future proofing tho.