Crossfire Question

Azza

Just curious about crossfire. I know for it to run with some graphics cards you need a crossfire master card or crossfire edition card (as opposed to the slave crossfire ready card) and of course a crossfire motherboard.

What I'm wondering is what type of master cards is there. For example is there a master card for each card such as the x1800xl, x1800xt, x1900xt and x1900xtx.

Is there just 1 master card for a series as in an x1800 master card and x1900 master card.

All the master cards I have seen for the x1900 seemed to be clocked slower than the x1900xtx. I assume both cards when running in crossfire run at the same speed so they would clock the xtx card down. So is there no such thing as running an x1900xtx in crossfire or is there an x1900xtx master card?

Any light spread on the situation would be appreciated.

8T8

All questions are answered in the Crossfire FAQ

You use a X1900 Crossfire master card with any X1900 GPU. Same goes for the X1800 series etc.

Clocks stay the same for cards even if different.

The low end parts X1300 & X1600 don't have a master card as they transfer the data over the PCI-E bus.

What ATI gloss over just so you know;
Catalyst AI Crossfire profile system is not accessible to end users so you cannot make your own profiles for games not supported by Crossfire. ATI's claim that you dont need profiles is PR bollocks.

When a game isn't supported by Crossfire it defaults to Supertiling mode this only works on Direct3D games.

It also gives variable performance increases you may get nothing or you may get something in a game as not all games benefit from this mode.

mewso

Apparently ATI claim that as of Catylst 6.5 in May you won't need a master card.

8T8

musician wrote:

Apparently ATI claim that as of Catalyst 6.5 in May you won't need a master card.

Not sure on that but I will have a look see, you wouldn't want to anyway as it would be transferring the data over the PCI-E bus which means you would take a performance hit. Fine for low end stuff but with high end GPu's all that data going back and forth over the PCI-E bus will eat into performance without a dedicated link to offload some of it.

I recall something about previous X800 generation with master-less Crossfire there was some issue with only half the frames being rendered without the master card I think.

mewso

Well it requires the new 3200 chipset (Mobo) which would imply to me that there may be some kind of bridge on the board to facilitate it.

Azza

I have a 3200 express chipset powering my machine and an x1900xtx card and if I got a master card to run it in crossfire would I see any performance benefit than running a master card over the standard x1900xt (however small the benefit is there one)

8T8

Of course you'd see a benefit but really only in games supported by Crossfire* and at very high resolutions with lots of AA and AF applied.

*Plus those that work well with supertile but I havent see a list anyhwere of what games not supported by Crossfire do.

Essentially you could run all your games with max details and 4xAA or 8xAA with 16xHQ-AF but you really need a 1600x1200 or greater capable display to get the most out of it.

The X1900XTX and the X1900 Crossfire Master will basically share & dynamically balance the workload so it's not an issue so both will be kept busy. In fact the X1900 Crossfire has the same clocks as the stock X1900XT according to here if you look at the first & second GPU.

Azza

Thanks for your help 8T8 and musician.

I was aware that not all games work with crossfire (but would I be wrong to assume at least some don't work with SLI)

I'm sure in time Crossfire will work on the majority of games. At least the new ones and I believe ATI have technically the better card these time although not as fast in current games (except at super high levels of AA and AF as well as high resolutions) which was the reverse situation with the 6800 series to X800 series a while back.

If I don't need a master card I may hold off and buy another x1900xtx in may then.

mewso

Yeah I've ordered a 3200 Mobo myself. I'm a bit of a die-hard ATI fan going back along time so I'm biased

Azza

Yeah I shot myself in the foot with my 3200.

I read how the old RD480 was poor and then I saw excellent reviews for the asus RD580 so I had a rush of blood to the head. I was not paying attention so entirely my fault. I ordered the Sapphire pure crossfire RD580 board as only 3200 express board available. So dazaled by its white appearance and the thought of matching the same brand gpu to the motherboard I did not pay any attention to the specs. So I only realised after I ordered I got the sucky southbridge with pants USB performance (not that big an issue to me) but it only had PCI slot (a big issue) then low and behold did I find out that the master PCI-E x16 slot was right beside and of course my gpu heatskin totally covers it...so zero pci slots for me except for 1 pci x1 slot.

So no sound card for me or or wireless network card. Frustrating because there is so much space for more slots...and why could they not have placed the master PCI-E x16 slot away from the only PCI slot and leave the slave slot beside it.

Otherwise performance is great on the board. Its mean't to be good overclocker too.

mewso

I ordered the Asus board. It's a good price on OcUK. It's on their This Week only section. An SLI board with a 7900GT was exactly the same price as the Asus Crossfire board with an X1800GTO so I had a similar rush of blood to the head and went with the Crossfire solution. The Asus board has 3 PCI slots so I should be ok.

Azza

Yeah reviews where excellent for that board your getting. If you do go for Crossfire you would only loose 1 PCI slot (assuming your gpu's cooler is half as big as mine).

Anyway I think I might hold off from buying a master card and buy another X1900XTX in May when the driver is released doing away with master card.