Question About Crossfiring My Old Computer

[LTC8K6]

You have double the cores to work on the video frames, so you have more processing power, but you are limited to the vram of one card. If both cards have 2gb, then you are limited to 2gb, because that's all one card can store in it's buffer. If one card has less than the other, then you are limited by how much that card can store in it's buffer. Both cards need to have the same buffer data at the same time.

 

[MongGrel]

Thread is definitely still open.

Yeah, and you've even started spamming other threads asking the same question.

:whiste:

 

[ZZZAAA]

You have double the cores to work on the video frames, so you have more processing power, but you are limited to the vram of one card. If both cards have 2gb, then you are limited to 2gb, because that's all one card can store in it's buffer. If one card has less than the other, then you are limited by how much that card can store in it's buffer. Both cards need to have the same buffer data at the same time.

I believe you are talking about mirroring which was used in the past (SLI?) where each card would put up a frame after another. Why would they need to have the same buffer data at the same time? You're saying they are both doing the same work at the same time which wouldn't give any performance boost at all seeing that the two cards are doing the exact same work? That would be a terrible analogy. Someone give me a source over here.

 

[ZZZAAA]

Also, LTC, by your logic I would be receiving back a total of TWO gb out of THREE gb of gddr5, not ONE, correct?

 

[ZZZAAA]

Anyway, I have two sources over here that these things stack. Anyone who's had previous experience with a similar build, please come in...

 

[ZZZAAA]

Ok, now I think I know it doesn't stack per se but at least two of three VRAM is in use.

 

[Shmee]

I had 2 6950's unlocked to 6970 shaders, in cf a while back. Both were 2GB though. Afaik, the VRAM doesn't stack. Also, the CF experience with cayman is not as good as it is with a bridgeless CF setup, such as with 2x 290s. This would be a better more modern setup. And it still only allows 4 GB of ram for use, unless you have 2 8GB 290s

 

[Headfoot]

Yes, the 6970's are on legacy drivers now but it shouldn't really matter especially if the games are built on directx 11 or older. I don't think they would program a game to run on a dual setup for each specific card individually. Either the game can use dual GPU's or it can't. I'm seeing a lot of reviews albeit in older titles where the crossfire gives greater than twice the performance of one card especially at higher resolutions (which means that the RAM is kicking in. Anyway, at least one source from any of you would shut me up. I don't think any of you have ever tried this kind of configuration before and I really don't trust your technical knowledge.

I own 2x 290 crossfire, as you can see in my signature, and it doesn't work 1/4 of the time.

Go ahead and buy your 6950 crossfire and see how often it work, and when it does work, see how often it scales well (meaning, 80% more fps or better).

Don't ask for advice then ignore it. Can we lock this thread?

 

[ZZZAAA]

OK, hopefully I didn't sound too rude over here. The internet can be very confusing sometimes with misleading people and articles. Thanks a lot all of you. Saved me some cash over here...

 

[Shmee]

Understood, you are absolutely right about how misleading the internet can be at times. Even "professional" review sites can be misleading, with their own bias agendas or paid for by sponsors who want them to review their products in good light.

My advice, as stated before, would be to get a modern DX12 capable card based on GCN, as pre GCN architectures are now EOL and don't support DX12.

We can help you out with recommendations for an upgrade if you would say what games you want to play, at what resolution, and the other specs in your rig. (to avoid CPU bottleneck etc)

 

[ZZZAAA]

Also need to know if I do buy 6950 1GB (which is on HOT DEALS btw), in what ways would I be able to use the second GPU in case it doesn't fully crossfire with RAM carrying over?

I also thought guru3d was a well-respected site and they wouldn't misinform me like that.

 

[KingFatty]

I just wanted to chime in and point out the error in the two sources you quoted on the previous page. Those authors were misinformed or didn't realize they were making misleading statements regarding memory in crossfire.

If anything, I think buying the 6950 1GB would be a fun distraction for a couple days while you setup crossfire, but then it would immediately get boring and then regret would set in for investing in obsolete technology. The novelty wears off really fast when you get that sinking feeling as you download old drivers that are no longer supported.

Do you have a particular game you want to use the cards with in crossfire? This won't future proof your computer, and would just waste extra energy. I don't see how it could make a critical difference in games, because you'd still have to turn down settings whether single card or crossfire on the 6950 1 GB.

I'd try to see it as making a sacrifice now to just suck it up and deal with having a single 6950 2 GB card, and then just keep the money you would have spent on the 2nd card to instead get a nice discount when you eventually upgrade. You never know, maybe you can also sell the existing 6950 too? (like if you have integrated graphics on the motherboard, just use the computer for browsing and other non-intense stuff).

 

[digitaldurandal]

I believe you are talking about mirroring which was used in the past (SLI?) where each card would put up a frame after another. Why would they need to have the same buffer data at the same time? You're saying they are both doing the same work at the same time which wouldn't give any performance boost at all seeing that the two cards are doing the exact same work? That would be a terrible analogy. Someone give me a source over here.

You went way off the rails and made like 20 assumptions to get there.

No the GPUs are not necessarily doing exactly the same work but everything is loaded into VRAM anyway. The assets they're working with are essentially the same. A ton of assets are loaded into VRAM before any work is ever done.

You keep saying you have two sources. I don't know why you asked the question but refuse to listen to any answers. Google it and research it yourself. Believe whatever you want and buy whatever you want.

 

[Crono]

That's what, a 200-250W card? What cooling do you have in that case? What are your temps with the card idle and at load? It's hard to tell from the pic, but it doesn't look like the card you have has a lot of space or unobstructed airflow in front of it... it's probably not even worth considering adding another card if it's going to run hot or require upgrading other parts of your setup, aside from the already mentioned limiting nature of 1GB VRAM.

 

[ZZZAAA]

Thanks for all your replies!!! I have decided to heed your advice and go for something new! I made a new thread about it in the general GPU forum. Any advice over there would be greatly appreciated!

 

[ZZZAAA]

I hope no harm was done by my stubbornness and refusal to listen. I understand that some of you are long-time members of this community and have heaps of knowledge and experience that I can only hope to attain one day. Again, thanks for reading and mods, lock this up please!

 

[Shmee]

Locked at OPs request. Good luck finding the new card.