Differences between the same card - GTX 580 - does anybody knows?

[rbuass]

Hi friends!
My friend got 2 GTX 580 Lightning brand new.
He is not extreme overclocker, then he told me i can choose one to use under Ln2.
when disassembling the boards, I noticed quite a difference in the two.
One is black and one brown.
The capacitors, while the same capacity, are also different.
In black you can read everything that is written on the chip and also see the nvidia logo, and brown, it is very difficult to read.
I think the same way as occurred with the GTX 480 (when the orange PCB were better than the green PCB), I wonder if anyone has any information on these boards or even on their batchs.

The black
46N3A8 1045A1
N3F110.000

The brown
06N3A3 1106A1
N3R791 01P

I appreciate any information on the extreme overclocking performance of the VGAs, cuz I only choose one and I can not test the second.

Below the pics to show the differences







Thanks in advance for all