CrossFire Question

[Wishmaker]

I currently have an XFX HD4890 XXX working like a Black Edition without any problems. Full details about my system can be found in my sig. I want to add a second XFX HD4890 XXX for a CrossFire set up but I cannot find another XXX in my area :mad:. I am still trying but if I don't find one, could I do a CrossFire set up with two different HD4890s? Will there be any issues? An interesting card I found is this one : HD4890 from Club3D with the following specs :



Anschlussart
PCIe 2.0 x16

Stromversorgung

Anschluss 2 x 6-Pin-Grafikkartenstromanschluss
max. Verbrauch ca. 190 Watt (bei Volllast)

Grafikchip

Bezeichnung ATI Radeon HD4890
Taktfrequenz 950 MHz
Stream-Prozessoren 800
Shader Model 4.1
DirectX Version 10.1
OpenGL Version 2
AMD Stream Ja


Please help me out here, I am not very experienced when it comes with CrossFire. Any input will be greatly appreciated.


Cheers,

Wishmaker.

[SoulsCollective]

Yes, you can Crossfire cards from different manufacturers and with different clocks. The faster card will be downclocked to match the slower, and if one card has more RAM than the other (although this isn't an issue with 4890s, because AFAIK there aren't any with more than 1GB of RAM) then the extra RAM will be ignored.

[Wishmaker]

Thank you very much for taking the time to reply. I really appreciate it. I am still learning about CrossFire. :hitself: So you reckon, that apart from the aesthetic aspect, they have different designs, if I put the XXX stock, the Club3D will run like the XXX and in 3D Mark I will have the equivalent of two XXX. Am I right?

[SoulsCollective]

I'm not sure, because I'm not familiar with the clock speeds of the XFX XXX series of 4890 cards.

Theoretically, using modern driver packages, the cards should work asynchronously (each with its own clock speed), but in my experience and in general received opinion, it seems that the faster one still drops to the speed of the slower. Even if you can get each card to work at a different speed, I really wouldn't, as using AFR with asynchronously-clocked cards will give you bad micro-stutter.

In any case, the important point is that yes, it'll work, this is just uncertainty around the edges.

[Wishmaker]

XFX decided on the following clocks on the XXX version :



Chipset ATI Radeon HD 4890
GPU Radeon HD 4890 XXX Edition
Bus Type PCI-E 2.0
GPU Clock 900 MHz
Stream Processing Units 800
Memory Bus 256-bit
Memory Type DDR5
Memory Size 1.0 GB
Memory Speed 3.9 GHz
Thermal Solution FANSIN


As I previously stated, the card works flawlessly on air in my antec 902 at 1GHz/4GHz frequencies. I can drop the frequencies to the default settings if need be. My problem is that I cannot find a similar HD4890. I can find under 900 MHz and above, as you can see in my post where I quote the Club3D specs. Your expertise in this area made it clear to me that worse case scenario, both the XXX and the Club3D will work at 900/3900.


What is the risk of the micro-stutter? It would be a shame to spend 200 euros on that club and end up with something which does not work properly :(.

[Razrback16]

I ran two 4870s in Crossfire before my current 4890s. The drivers allowed me to clock them at different speeds -- now whether they did something internally to match each other when in 3D apps, I don't know -- I do know that even after gaming, one would report stock clocks as it should and one would be overclocked where I had it without any changes (this happened when I had my original 4870 on water and overclocked and was waiting for my second waterblock for the 2nd card).

[Wishmaker]

Thank you for the reply. Seeing you have these in CrossFire, what are the chances for micro-stutter? Also, I seem to have hit a snag :(. The X58 UD3R was designed for CrossFire but the space between cards will be non existent. Another user on youtube has HD4890 in CF on X58 UD3R and he says there is a 10 mm space between cards. This is getting me worried because the top card won't be able to "breathe" properly :(.

[Razrback16]

I have not noticed any micro stutter. I see people talk about it on the forums, but I haven't actually encountered it. All games I've played run smooth as silk. Crysis is the only game I can't max out in terms of settings, but the settings I do run are nice and smooth (1440x900, all settings on VERY HIGH with 0xAA/16xAF -- this is why I turned the res down so that I could enable all the cool eye candy features in the game -- looks great and plays great). Far Cry for example I play in 1920x1200 at 16xAA/16xAF with everything on maximum -- smooth as could be.

[Razrback16]

Also one piece of advice I want to add for you since you mentioned cooling. If you plan on extreme overclocks, do not put a full coverage block on these cards. They do not cool the VRMs sufficiently for volt mods to hit high clocks. I had both of these 4890s voltmodded to 1GHz core and in certain games at certain high utilization areas they would lock up - I set up monitoring apps and the VRMs were hitting ~140-150*C on WATER with a triple rad and a dedicated loop. My cards could easily go past 1GHz -- the core temps are very good at those speeds @ 1.41 volts, but the VRMs just get out of control -- this is why I backed voltage back to stock @ 1.31 volts and just have a moderate 75MHz core overclock on stock volts to keep VRM temps under control (@ stock volts and these clocks they run around 100*C -- good mem clocks though w/ the full cover block). Just something for you to keep in mind.

[zanzabar]

the cards will run at different clocks it will not down clock anything, the ram will be dissabled if they are different sizes though.


and almost all referance 4890 will clock about the same to 1050mhz with 1.4-1.425V and all that the black gets u is the black pcb and the stock voltage so if u match the settings or flash the bios to the xxx they will work identically

[Wishmaker]

Once again, many thanks to everyone. I appreciate all the input and like this I learn a few things as well. I managed to find another XXX after 3 days of constant searching. It will be shipped soon and I will put in my case. The problem I am facing is this one :

http://i266.photobucket.com/albums/ii256/Integrabyte/I7002.jpg
http://i266.photobucket.com/albums/ii256/Integrabyte/I7003.jpg


As you can see from the photos, the space between them will be non existent. What am I going to do with the one on top? It will not be cooled at all. What about the Bridge? Won't I have to bend it at a slight angle so both cards can connect in such a short space?


A fellow member told me one can flash the XXX to the Black Edition. Knowing that the XXXs are highly overclockable and stable, I might add, can anyone point me in the right direction? A guide, a topic?


Another quick question, is this score limited by the CPU or it is an okay score for an XXX card with those clocks.


http://i266.photobucket.com/albums/ii256/Integrabyte/13843.jpg

[SoulsCollective]

Having that small a space won't be an issue, nor will bending the Crossfire bridge. Temps on the top card will go up, sure, but seeing as how the fans almost never spool up to full at stock anyway you've got lots of fan headroom if you don't mind the noise. Otherwise, the solution is watercooling.

[Wishmaker]

I will have the card in roughly a week. I will set it up and will revert to you guys. Regarding water cooling, it is an option, but voiding my warranty is what's holding me to do it :(.


This is what I wanted to get :

Aqua Computer AquagratiX HD 4890 (RV790)


http://www.hardwareoverclock.com/Wasserkuehlung/AC_Aquagratix_HD4890-001_small.jpg

http://www.hardwareoverclock.com/Wasserkuehlung/AC_Aquagratix_HD4890-003_small.jpg

http://www.hardwareoverclock.com/Wasserkuehlung/AC_Aquagratix_HD4890-005_small.jpg

http://www.hardwareoverclock.com/Wasserkuehlung/AC_Aquagratix_HD4890-007_small.jpg

A small test for : XFX HD 4890 1000M Black Edition

http://www.hardwareoverclock.com/Wasserkuehlung/Aquagratix-4890-prime-Fur-benchmark_small.jpg

http://www.hardwareoverclock.com/Wasserkuehlung/Aqua_C2.GIF

http://www.hardwareoverclock.com/Wasserkuehlung/Aqua_C1.GIF

[SocketMan]

I will have the card in roughly a week. I will set it up and will revert to you guys. Regarding water cooling, it is an option, but voiding my warranty is what's holding me to do it :(.






XFX allows users to modify the cooling,check their site for more details.
Another thing is that the price for 4890 (and others) will most likely
drop,once the new DX11 cards come out ~Sep23 or there abouts.

[Wishmaker]

The card arrived yesterday. This is the space in between :

http://i266.photobucket.com/albums/ii256/Integrabyte/XFX.jpg


As one can see, not a lot of space. Fortunately, the upper card is hotter by only a few degrees in idle : 62 as opposed to 60 (the temp before). The lower one is 57 due to the direct venting of the PSU. I ran FURMARK at every possible resolution, eventhough I have high idle temps, in full load the upper card does not go higher than 82.

[pissboy]

Unscrew the cards, move the top one up a little and the bottom one down a bit. It should buy you another 1mm or so of space. I did that, but I didn't notice much improvement.

I'm looking into picking up a pair of EK-FC4890 LT blocks right now, kind of a tight fit to cram another two blocks into a MATX though. :)

[Wishmaker]

Thanks for your insight. At the moment I will leave them like this. They are behaving normally and there is no need to bend them or move the top one. I did notice some interesting artifacts in Flight Simulator X tho :P.