Crossfire - 16x16 necessary?

[Caldezar]

So I've been doing quite a bit of reading on this, and it seems to be basically a coin toss on people's opinions. The question being: Is full 16x16 2.0 crossfire support that large a jump in performance over 8x8 2.0? (Real world gaming)

The situation is that I have an 8x8 2.0 board (see primary in sig) and I'm going to be running 2x 4890's in crossfire. Should I seriously consider moving from a 790x to a 790fx board to get 16x16? Obviously I understand that benchmark numbers are higher for the 16x16, but does current game development take advantage of the jump? Is it really worth the $150 - $200 to get a new board? Is crossfire in 8x8 a waste?

And before I get comments about moving to a new board for 16x16 AND DDR3, forget it. I don't want to spend the money it'll take to buy the RAM. The only real option I'm considering is a jump to one of the few AM3 DDR2 boards with 16x16. Probably this one. But I don't want to drop the money for it unless it's a noticeable performance boost.

Thoughts? Any educated input would be appreciated. (Please list reasons for answers, not just assumptions.)

[Chilly]

With 5970's perhaps, with most other cards, while its not an ideal set up, there are very little bottlenecks to speak of

[CMetaphor]

Originally Posted by Chilly

With 5970's perhaps, with most other cards, while its not an ideal set up, there are very little bottlenecks to speak of

+1. Only with very high-end cards will you see any noticeable drop in performance running 16/8 or 8/8. I think its in the area of a 2-4% drop in framerate in games - aka not much at all. Don't worry about it - keep your board.

[Caldezar]

Thanks for responses. That makes me feel a little better since I'm already having to buy a new PSU to do this. Of course, I could have bought an fx to start with, but I never really expected to be running crossfire.

[Dr_BenD_over]

I saw a review somewhere that showed real world performance differences between assorted configurations, but I can't find it now. I'll keep looking IIRC for the most part, with the cards available at the time, x8/x8 was sufficient.

http://www.tomshardware.com/reviews/...ress,2095.html about 1 year old results

[IRQ Conflict]

Here you go: AMD Radeon HD 5870 PCI-Express Scaling

[MarkOne]

I will sale the 4890 and get a 5870, and here why

you already ready to may be spend $ 200 for a new board, and an other $ 200 for an other 4890, so $ 400, if you sell the 4890 , $ 160, that make you $ 560 for a 5870

i test the crossfire and i was not impress. Crysis was slower, and i have few bug that was repeatable in xfire but not in single mode

and don't forget the power usage will be less too, same for the heat

I sell my second 4890 for this reason. i prefer have a single card now

[Caldezar]

Originally Posted by MarkOne

I will sale the 4890 and get a 5870, and here why

you already ready to may be spend $ 200 for a new board, and an other $ 200 for an other 4890, so $ 400, if you sell the 4890 , $ 160, that make you $ 560 for a 5870

i test the crossfire and i was not impress. Crysis was slower, and i have few bug that was repeatable in xfire but not in single mode

and don't forget the power usage will be less too, same for the heat

I sell my second 4890 for this reason. i prefer have a single card now

Actually, I'm looking at NOT buying a new board. And I already have the second 4890 shipping to me. The only thing I'm short at the moment is the PSU. (Only running a 550 atm) So I don't want to sell 2 4890's and have to still spend another $200 - $300 on top of that for a GPU.

Thanks for the link IRQ. Looks like the difference between 8x and 16x is extremely minor, even in a card much faster than mine.

[cozmosland]

yes im pretty sure you need at least a 650 for a dual 4890 setup
you could have gotten away with 2 5770's with it probably as the power req is alot less.
but your not. so go get yourself a nice shiny new power beast

[Caldezar]

Actually, an XFX 850W Black Edition is in my future. =)