are you sure the 1 beep and 6 beeps mean a card problem?
No, I'm not sure at all. To be honest, I can't find any AMI/AWARD/PHOENIX beep code which matches this one exactly. There's several things which the POST test checks right at the beginning & we know the test is failing early on otherwise you would a display on the screen.
One of the first things is the ram (first 64k of ram) but because you got a different beep when you removed the memory, this suggests that the 1-6 beep code is probably not a memory error.
Other things that are checked include the video, cpu & bios.
If the post test was failing on something which is checked before the first 64k of ram, then removing the ram shouls make no difference to the beep code. This suggests in your case that everything upto & including the 64k test is passing. If the post test was failing on a check that takes place after the video check, then removing the video card should result in a different beep code (it doesn't). This means (in theory) that either the video check is failing, or some other check that occurs in between the 64k & the video check is failing.
I'm not ruling out the cpu or even the motherboard as being the culprit here, it just seems more likely that it's video related. This may not necessarily mean that the video card itself is the problem either - it could still be a fault with some part of the motherboard connected to the video controller or simply a case of the video card not being correctly fitted. It would of course have been helpful if you had the D-Bracket for the board, as this would give a more precise & conclusive diagnosis.
Before you RMA anything, it may be worth just double checking the cpu - i.e that the cpu & heatsink etc are correctly seated.
From what I understand, as you bought an open box motherboard, you have limited time in which to return it (as I'm sure you are aware) so obviously if you are going to RMA the board, you will need to do it now. It may not be a bad idea - from what I've read on Neweggs website, there do seem to be a lot of DOA boards.