Hi my friendHello, welcome to SlateDroid.
The A8x GPU is SGX540 as in A8, the difference is the processor, in A8 is S5PV210 and A8x has S5PC110, same power but less consumption. I have installed some games in my A8x, Asphalt 5 and 6, PES2011, Fast andFurious 5 and NFS Shift. Asphalt 5, NFS and PES2011 work perfectly, shooth and fast, while Asphalt 6 and Fast 5 aren't totally smooth but are perfectly playable. With a better firmware i think this tablet will run faster, only need best optimization.
Answering your next question i can't complain with my A8x, worked without any problem since i had it in my hands. I have read about some units faulty, but i think the number isn't high compared with the totally operative units. I hope the A8x users tell us their impressions about it.
Which Firmware are you using on you A8X to play these games (Asphalt 6, Fast and Furious 5 and NFS Shift) and what is the version os the apk (Asphalt 6, Fast andFurious and NFS Shift).
Please make thing easy to me my friend.
I thank you for your atention.