SLI / CrossFire FAQs

[Guest]

hy guys i wanna build a new pc (for gaming) and i need help , i wanna buy a best processor and a better video card , about ram i think will be ddr2 4gb max mhz possible (if u think will be better buy ddr3 plz tell me) buget is 500 Euro, i whant this pc to handle games in the future 2/3years so...i was think about :
procesor: AMD Phenom X4 9850 / Intel Core 2 Duo E8400 / Intel Core 2 Quad Q9300 to Q9650
video card: Sapphire Radeon HD 4850 X2 2GB
rest it doesnt matter to me , just a v good power suply plz help me with ur's idees if u know a better video card on proceesor plz tell me tnx for help i will w8 ur reply or plz contacte me on ady_jl@yahoo.com tnx again guys

 

[Maziar]

You posted in the wrong section,please post in here:
http://www.tomshardware.co.uk/forum/forum-13.html

 

[icstm]

Fans and Power:

Hi guys,
(my first post here)
I have a quick question, which should have a quick answer.

Let's pretend I was about to buy the 4870 or two 4850s in CF:
Assuming that each card's power use and fan noise are similar:

- will the CF solution always sound twice a loud?
- use twice the power?
- in normal web browsing does one of the cards switch off (like a low power state found on multi-core processors)?

According to the GPU charts there are some cheap SLi/CF configurations out there, but I am wondering if they complicate things.

On another note, where is a good place to sell an old AGP card?
I have an BFG 7800GS OC which is way too powerful for my XP 2800+ (Barton) CPU unless I am work out a way to better o/c it

 

[Maziar]

Hello and welcome to the forums
2x4850s will be louder than a single 4870 and requires more power.
And no none of the cards switch off

 

[nukemaster]

icstm,

Check out the link below for info on video card power usage both at idle and load.

http://archive.atomicmpc.com.au/forums.asp?s=2&c=7&t=9354

 

[Maziar]

Good link with useful information,thanks nuke

 

[moe2freaky]

I have a question and yes I am a Noob so please don't flame me.

I understand that in SLI/Crossfire mode the ram from the second card is not being used.

What's holding Nvidia/AMD from accessing that extra ram on the second card?

Kind Regards

Moe

 

[Maziar]

Do you mean that why for example when you CrossFire 2 512MB cards,the memory won't be 1GB?

 

[moe2freaky]

Do you mean that why for example when you CrossFire 2 512MB cards,the memory won't be 1GB?

Exactly. Cheers

 

[Maziar]

Well it's because both cards work separately,so for example when you CrossFire/SLI 2 512MB cards,each card works with 512MB of memory,and the memory doesn't double.(You won't have 1GB memory)

 

[blotkis]

Mazier:

Will the following setup work? -

3 24" monitors, 2 plugged into 1 card and the 3rd plugged into another that will be the primary (both 5850 graphics cards).

I'll keep Crossfire off so I can use all 3 screens, but if I want to game will it be possible to have both cards in Crossfire mode to game on my primary display (i.e. the monitor plugged into the primary card only). I think the 2 other monitors wont work w/ Crossfire enabled but that's totally fine.

Also, if this is possible can I just switch Crossfire off through CCC or does it require a reboot? Thanks a ton.

 

[Maziar]

http://www.guru3d.com/article/ati-eyfinity-editorial-review/2

"For those that are wondering, would it be possible to use say two Radeon HD 5870 cards with each driving three monitors ? That's a no. CrossfireX will not support/allow this, so you'll need one primary cards from which all monitors lead."

About your last question,well you can disable CrossFire from CCC but i am not sure whether it will require a reboot or not

 

[austinkarl]

hey friend the information is very useful and informative. i think the message will be not useful to me but to the beginners to graphics.

 

[Maziar]

Thanks

 

[brandonvi]

I know this was more then likly posted somewhere in the last 11 pages of this post but i really dont want to read all that if somone can answer it for me

can SLI or crossfire be done with cards of different generations meaning can you crossfire a 4870 and a 5870 or a GTX 260 and a GTX 360 or GTX 460

well i guess the GTX 300's are not out yet but somone should atleast know if like you can put a GTX 260 with a 9800GT and from that be able to draw a conclusion

 

[Maziar]

You can't crossfire a 4890 with 5870 for also GT 300/400 series aren't out yet but i don't think you can SLI them or combine them with GTX 260 since they have different architectures.

 

[Guest]

I liked the information, though I think I was generally aware of most of what I needed from what you provided already. I am looking for information on how your CPU can bottlenecks (technically) a GPU SLI configuration. How can you figure whether or not your CPU will factor into your planned SLI setup? I didn't see anything about that here. Thanks for redirecting me to a post or answering my question in advance!

 

[Maziar]

Well CPU bottleneck depends on which games you play and also the resolution that you play at,as an example most FPS shooter games are GPU-limited but there are some games which benefit from a great CPU too,so for example when you play a game (which benefits from a good CPU) with a good VGA card and a slow CPU then you won't get the performance you need

 

[tommy6860]

Very informative, but one thing I would have elaborated on a bit more was the fact about having two cards in SLI/Crossfire modes, and how that setup doesn't mean doubling the memory. I admit, I've had a misunderstanding on how that worked, up until I read this here. But, doesn't having that two card setup improve how graphics perform, and isn't the memory from both cards still used across (or from the) two cards anyway?

Otherwise, it would (seem) to be a moot point and a complete waste of one of those cards to have that set-up.

 

[Maziar]

When you use 2 cards in either SLI or CrossFire,the memory of both cards are used but it doesn't double the memory,let me tell you with an example,when you use 2
ATI HD 4850 cards in CrossFire,both 512MB RAMs of both cards are used so it means you have 2 cards and they use the 512MB of memory so you won't have 1GB memory

 

[tommy6860]

When you use 2 cards in either SLI or CrossFire,the memory of both cards are used but it doesn't double the memory,let me tell you with an example,when you use 2
ATI HD 4850 cards in CrossFire,both 512MB RAMs of both cards are used so it means you have 2 cards and they use the 512MB of memory so you won't have 1GB memory

Thanks for the reply, and I am not trying to sound daft, but your reply basically says the same thing to which I inquired initially. Doesn't both cards total 1g of memory. As I ask before, what is the point of having (as in your example) two cards of 512mgs for a total of 1g, if all of the memory from both cards isn't going to be used? It also makes moot even the x2s.

 

[Mereel]

Can you SLI a 9800+ and a GTX 250?

 

[nukemaster]

Nope, the cards for SLI must be the same.

But you can use the 9800+ for physx
EDIT

@ Maziar, grats on mod status!!

 

[Mereel]

Thanks. I just thought since they were so similar...

 

[nukemaster]

Thanks. I just thought since they were so similar...

They are both die shrunk G92's but i think the only way one could remotely do it would be to flash them both to 9800GTX+'s, but i would not recommend it, incase there are other side effects.