CrossfireX Compatibility

[zxnet2k]

Hi all,

I'm buying a new AMD board that is using the 780G chipset - and reading the features it mentions that the onboard graphics ATIRadeon™ HD 3200 can be used with an additional graphics card to utilise the CrossfireX. The graphics card I was planning to get was the XFX HD 4850.

1) Will these 2 actually be compatible with Crossfire?
2) If yes, would there be a significant performance increase over just using the 4850 alone?

[Shedlife]

I would image it means with another HD3200 rather than ANOTHER graphics card such as you're 4850.

[scaryjim]

zx - which board? Officially the 780G doesn't support enough PCIe channels for Crossfire, but some board manufacturers produce boards with two physical X16 slots which makes crossfire *possible*. If that's the case, you'd need a second 4850 to take advantage though - hybrid crossfire (combining the onboard HD3200 with a discreet card) only works with HD3450 / HD3470. And your single 4850 would be a *lot* faster than that combination

[Blaineoliver]

No it does not mean another 3200, it means and compatible card.

An ATI Hybrid CrossFireX™ system includes an ATI Radeon™ HD 2400 Series, ATI Radeon™ HD 3400 Series or ATI Mobility Radeon™ HD 3400 Series graphics processor and a motherboard based on an AMD 780 integrated chipset, all operating in a Windows Vista® environment.

Only on vista and those chipsets, not that you would get any improvement with the onboard crossfire X.

[zxnet2k]

hi guys thanks for the quick response - the board is a GByte GA-MA780G-UD3H

I think I'll be happy with the HD 4850 for the time being, although at some point in the future could it support crossfire with 2 HD 4850's?

*edit* - I understand now, thanks for the information guys I think I'll be happy with the performance of a single HD 4850 anyways =)

[scaryjim]

Ah, one of Gigabyte's classic shoehorned Crossfire motherboards.

The board does support 2x 4850 in crossfire, but the second PCIe x16 slot is only electrically x4 - so it only has a quarter of the bandwidth available to it. If you're gaming at resolutions that the 2x 4850 could get their teeth into it would probably end up bandwidth starved.

So, probably not worth crossfiring really, unless you fancy picking up a Sapphire 4850 X2 1GB for £136

[Powderhound]

I think he's asking about Hybrid Crossfire rather than crossfireX, but this will throttle the HD 4850 down to the HD 3200's speed, so you can ignore that feature.

[scaryjim]

I think he's asking about Hybrid Crossfire rather than crossfireX, but this will throttle the HD 4850 down to the HD 3200's speed, so you can ignore that feature.

No it won't, it won't even work. Someone's already posted a snippet from the AMD website on this thread that clearly states which series' of cards you can use.

Yes, the OP was asking specifically about Hybrid Crossfire (which you can't do with a 4850 under any circumstances) - but I thought it worth mentioning that his board would also support a limited version of real crossfire. Incidentally, I believe it would also support running 2 discreet HD3450s in 3 way crossfire with the onboard, although I could be wrong...

[sammorris]

Even if it did work, you'd never see any benefit, the HD4850 is at least 10x faster than the HD3200. With perfect scaling, you'd get maybe a 5-10% performance boost in games.

Scaryjim: Why is "shoehorned" crossfire a Gigabyte trademark? The limitation of the electrical speed of the PCIe bus is the chipset, not the board manufacturer...

[TooNice]

So, probably not worth crossfiring really, unless you fancy picking up a Sapphire 4850 X2 1GB for £136

That affordable? I will resist. Damn you

[sammorris]

1GB is a bit of a letdown for CF, but at that price it really is an incredible deal, if it fits in your case of course. The HD4850X2 PCB is damn vast.

[scaryjim]

Scaryjim: Why is "shoehorned" crossfire a Gigabyte trademark? The limitation of the electrical speed of the PCIe bus is the chipset, not the board manufacturer...

I've seen more Gigabyte boards sporting a second physical X16 with electrical X4 than any other manufacturer (otoh, anyway) - but it certainly isn't a "feature" that's exclusive to Gigabyte.

However, most manufacturers have just accepted that 780G can't support enough PCIe lanes and only put 1 physical x16 slot on the boards...

[sammorris]

There is, of course, the possibility for using other components instead of graphics cards in that slot. Granted, it's not very likely, but a PCIe RAID card for instance would still run better at 4x than 1x...

[scaryjim]

There is, of course, the possibility for using other components instead of graphics cards in that slot. Granted, it's not very likely, but a PCIe RAID card for instance would still run better at 4x than 1x...

If the PCIe raid card was meant to run at x4 then it would have an x4 connector and wouldn't *fit* in an x1 slot. Gigabyte could've put a physical x4 slot on the board instead (which would also take x1 cards, of course). There is little excuse for a physical x16 wired to electrical x4.

[sammorris]

I mean a 16x card running in a 16x slot electrically at 4x.
Are all these boards PCIe 2.0? If they are it's perfectly acceptable to run CF through them, but PCIe 1 4x would admittedly be on the slow side.

[Bill@W]

I’m rather disappointed with my hybrid crossfire experience: Asus M3A78-T which has 790GX chipset which means an integrated Radeon 3300 GPU. I installed a Radeon 3450 PCIe card to run in hybrid crossfire with the onboard gpu. The CPU is an AMD quad 9750, and there’s 2gb of memory. OS is Vista Home Premium 32-bit.
Using the Vista experience index, the graphics score is a paltry 3.6, and the gaming graphics index is 4.
What would be an appropriate PCIe card to use instead of the ATI 3450 (disabling the onboard 3300 and giving up on hybrid crossfire) to get a vista graphics index in the upper fives? I’m not looking for a fast gaming card, all I do is image manipulation, and as a matter of principle I don’t believe in paying more for a graphics card than for a motherboard or CPU.