XFX HD 7970 DD Black - I'm about to chuck these out the window!!!

[sighle]

Ok so I'm going to keep this as short as possible but here goes...

I have 3 of the XFX 7970s that are so well known for their low hash rates for Scrypt mining.

1 of them is fine, but 2 of them(from a separate batch, according to serial numbers) have the low hash issues.

I followed the instructions here: https://litecointalk.org/index.php?topic=8984.0 to flash a new BIOS onto the cards.

I tried the suggested BIOS in that thread on the 2 cards that are having issues and it gave me black screen. I then found another thread that gave information for the UPDATED BIOS directly from XFX for that card. The flash went perfectly, all of my cards are operational and the BIOS on all 3 of them is identical.

Here's where is gets weird... The BIOS, model number and everything is identical on these cards. I tested them individually and they ALL hash at ~730kh. However, when I install them all into the same mining rig, 1 of them hashes at ~730 and the same 2 that had problems before hash at ~360.

What. The. Fuck.

Has anyone seen anything like this? Does anyone have any ideas why this would be happening?

[ghur]

Are you keeping track of the temps?

2 of them might have cooling problems due to having their intake blocked by the card above.

[sighle]

It's not a temp issue. When I start the rig they hit their max hash rates before they hit 60C and cap out at the ~730, ~360, ~360. They never go above.