Crossfire adventure. Starting with a fail.

So after my 5870 oc adventure and heatsink adventure comes to crossfire adventure.

I bought a 5870 and crossfire cable from ebay. It came with the heatsink and is being sold as 14 day DOA protection. To start, it wasn't a 5870, rather, it was a 4870! I could tell by the GPU die alone but I have my old 4870 and all the stickers pretty much match between the two cards.

Nevertheless, I threw it in to at least try to test the crossfire cable. No start up. No beep code, no BIOS screen, just a blank screen. I disconnected the crossfire cable from my 5870 and still had the same result. I do have a working fan in the second slot so that wasn't causing the issue. The moment I totally unplug this suspect card the system starts up again.

So now I cannot really test the crossfire cable unless of course I try using my old 4870 which I know works. I will probably do that later today or tomorrow.....

The next question (as I try to sort out sending back the bad 4870), do I want to run crossfire with a 5870+4870 assuming the cable works? I know it brings it down to 4870 level but are 2 "4870s" better than one 5870 for the moment? Also will this force me down to DX9 instead of DX11 or does the main video card control that?

 

Firstly, you should return it and the seller should refund you if he/she sent wrong card.

You can't crossfire 4870+5870. It's just not possibile.

The 4870 supports DX10, and with my last vBIOS for 4870 you can overclock the card to 5870M performance level
So you would be essentially running at 5870M crossfire preformance if both cards can OC to 700/1000

vBios is found in this thread
http://forum.notebookreview.com/ali...mod-overdrive-undervolting-work-progress.html

 

but I don't have 2 (working) 4870s- or well, maybe I do because I tried to crossfire it with my 5870 but nevertheless I don't want to unbox her and see if it works alone.

I did some research- you are right, with NVidia sli requires the exact same card but ATI crossfire requires the same series. I don't know why I thought I could mix a 4xxx and 5xxx

 

You can only CFX cards that have the same die. Active shader clusters don't matter unlike SLI.

The following are the only CFX configurations that will work in theory the R2.

4870m + 4870m
5870m + 5870m
5870m + 5850m (if you can find one - really rare MSI cards)
5850m + 5850m
6970m + 6970m
6990m + 6970m
6990m + 6990m
7970m + 7970m
8970m + 8970m

 

I cant help myself I have to play around!

First and foremost the seller said to send back the card for a refund. They are also going to review their stock because they have two other boards they are selling as 5870s. If they really have a working 5870 I will take that.
So I put my old 4870 back in and installed the card and cable I received today. It all works: both the secondary card and the crossfire cable. The 4870 is still going back to the seller but I only had 14 days to evaluate the cable and it would suck if I get this sorted out and then the cable is bad. The average price for those things are like $50!

 

Great news , did you also make sure that it says crossfire enabled?
I can get both 5870M in my M17x R2 but for some reason they just wont CF, (Both are recognized, but in CCC i get Crossfire disabled).

 

Yes, it did say crossfire was enabled. Even GPU-Z allowed me to switch between the two of them (one was running a degree or two above the other).
Windows 7 indexing dropped me to 7.2 though, it was 7.3 with the single 5870.

I didn't run 3dmark though. I just wanted to see if
the card was dead,
cable was dead,
card was definitely a 4870 (there are no marking that specifically say 4870 on it)

The strange thing about ccc was it automatically enabled crossfire. I did have to uninstall the drivers for the 5870 and download the 4xxx legacy drivers from ati's website but in the control panel "enable" was already checked and I had the option to disable only.

 

Great, so the cable is verified
WEI just sux, dont rely on it a little bit.... (except if it rates your CPU under 5.0 xD)
I think thats the way it's supposed to be (never worked for me though)...