Great, that's what I wanted to know. Thanks PoorBoy.
When it stops raining I'll get some resistors and make up 2 dummy plugs to use.

I dont have the problem of dual cards, so with that caviat ....

I have seen on other boards/projects this hassle going on, and extending the desktop across all cards appears to have worked for many. It does not appear to be a silver bullett, but it appears to be part of the solution mix. For some it made no diference, others it did (some before dummy plugs, some after attaching dummy plugs)

Worth at least keeping it in the back of the mind as hardware configs change in response to the problem - appears to have worked for some people.

Regards
Zy

Yes I understand, I had that working when I had 2 single cards. But now when I try and extend desktop on display 2 and 3 I lose the taskbar and icons. They are not on display 1 either. If I duplicate desktop on display 2 and 3 and make it my main display I get taskbar and icons on the one display. If I use just 2 cables the second core of the 5970 goes to sleep if it is idle for any length of time and won't always wake up.

I think I'll get another DVI cable as well as some resistors, the display port seems to sometimes lose the link and is temperamental.

Fisrt of all, special thanks to "The Gas Giant" and "David Glogau" for posting precisely the solution (in my case) to my 3GPU's issue.

I did turned off CrossfireX mode and removed the crossfirex bridge between cards. ALSO, I moved the second card (HD5870) from PCI-e_2 slot to PCI-e_3, so there's more space between them and that brings a reduction of 10°C... so now I'm running both cards between [85°C - 93°C] at full load, activity on CCC says its 93% at peak... (Yes, sometimes I reached 105°C on the HD5970)

My main monitor is at 1st DVI port on the HD5970 and I borrowed and old monitor just to plugg at 1st DVI port on HD5870 and... Voila!

(Had to restart Windows to detect that last card) but BOINC did recognice 3 GPU's and now I'm crunching at 1:40mins overall... even 1:00 - 1:20 on the HD5870 !!!

I'll try with the dummy plug.

And for scottishwebcamslive I have to say I'm running with a PSU CoolerMaster 850W and everything seems fine. So, yours should be no problem

Dummy plug...

DD,

For those who run boinc on multi-gpu setup. "Always use dummy plugs!"

Even if some reported they have no problem running without dummy plugs, whats the problem in using 1/2/3 for peace of mind. It only cost a buck or two to make one depending on the quality of the adapter. If your card already have vga connector you can bunch-up 3 resistors by glue or something and insert the resistor legs on the proper holes. But for safety and ease of use, a plug is better.

You only need:
1 DVI-VGA adapter
3 1/2w 68-100 ohms resistors

Note: 1/4w seems okay but they're too thin and 1w is too thick

Since cards nowadays include dvi-vga adapters in the package, you only need to buy the resistors.