1 Bitcoin for the one that solves my problem!

[RoadStress]

Otherwise.. grab a multimeter and stick it in one of the 12V rails, watch the amperage when you boot. If it drops significantly then you have a PSU issue.

More than likely however, is the overclocking, if the system bus is out of clock with the PCIE frequency video will fail to boot. I had a 4890 that worked fine in my X38, but I had to reset RAM timings to get my 5770 to work.

i don't overclock my system and i'm 99% that it's not from my PSU. i will try a 6850 (i see that uses almost the same power as 5870) and will see then. i have tried with only one memory stick and it doesn't work so it shouldn't be from ram. at this point my guess is that it's a faulty card

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[LegitBit]

i don't overclock my system and i'm 99% that it's not from my PSU. i will try a 6850 (i see that uses almost the same power as 5870) and will see then. i have tried with only one memory stick and it doesn't work so it shouldn't be from ram. at this point my guess is that it's a faulty card

It would suck if that is the case.. though certainly isn't out of the range of possibility.

Ship it back if you can, but don't expect a replacement.

Good luck man.

[computerparts]

If you tried that card in another system and it worked, then it sounds like you have a bad motherboard to me.

[supa]

If it's a crossfire mainboard, have you tried disabling crossfire?

Are you using the crossfire connector?  Did you use them in the previous system?

When you cleared CMOS - are you sure there aren't any settings for video?  Some older boards will have a toggle from PCIe or PCI (or even AGP), newer boards might have PCI/PEG.  Boot with a working card and check.

Someone mentioned PSU draw - this is a good place to look.

You mentioned you are 100% sure you have connected and powered the 6pin power connectors on both cards.

And you definitely hear beeps, right?  One of my ATI cards will only appear as a valid adapter if there is a DVI cable in the bottom (opposite the PSU) DVI connector - no idea if my card is jacked up, but you could try that.