Thank god both my T61's have the nVidia A2 chipset. Awesome. What a relief?
This doesn't really matter and is no indication for a faultless chip at all. You should have read on further in this thread than just the first page to find the relevant information. The only thing that would give some real relief would be to find out the exact date code printed on the physical chip which indicates the actual production time of the chip, and which cannot be read out with any software utility like GPU-Z.
To verify the actual production date, you have no other means but to open up the machine, remove the cooler unit from the board, wipe off the thermal grease from the chip having the term nVIDIA printed on it, and note down the numbers printed on the physical chip. For a photo showing what you can expect to see, please refer to forum.thinkpads.com/viewtopic.php?p=633146#p633146
(which BTW is on page 5 of this very same thread). The article forum.thinkpads.com/viewtopic.php?p=627753#p627753
shows two samples explaining how to interpret the date code printed on the respective GPU chips.
Here is what was printed on one the faulty nVIDIA GPU's from one of my own broken T61's and, as you can see, the pointless A2 indicator is also present:
The relevant information is the date code shown in the right half of the second line. In this case, it refers to year 07 and week 51, meaning that it was produced during the third week of December 2007, which is about half a year before the production of fixed chips finally happened.
Here is a sample of a fixed GPU, which was present on the replacement mainboard for above mentioned machine, and which i subsequently sold in favour of an T61 with Intel graphics as i have no use for any power hungry GPU performance:
According to the date code shown in the right half of the second line, this chip was produced by nVIDIA in year 10 and week 41, meaning it was produced during the first week of October 2010. So this board is definitely on the safe side and the buyer of this machine is most probably still happily using it for his daily work.
When reassembling the machine after having performed the above described inspection, make sure to apply some fresh thermal paste on both the GPU and the CPU. Don't even think about performing this visual inspection before you haven't purchased some suitable thermal paste to apply, unless you purposedly want to fry your T6a's GPU and CPU afterwards.