Hello, long time pc owner, new to apple. Just bought my first apple, the new Imac with the 680mx card, received on March 16th. I installed steam and was playing counterstrike, not a vey graphic intensive game. After 3 weeks of ownership, I got on and about 10 minutes into gaming suddenly this intense lag came in and made it impossible to play anymore. I could barely move the mouse cursor over to close the game and after that all my applications would lag for about 10 minutes. Loading an application that would open instantly would take around 5 seconds to load. I looked at the activity monitor and noticed my system was at 70% usage with no programs running. I bought an optical drive and another game and had the exact same problem so it wasn't a software issue. Spent some time trying to figure what could be wrong then called Support. Apple support is great, very quick to call me back and try to help. They could not figure out the problem over the phone, and I have an appointment to take it in this morning. I am curious if i could ask for a replacement? I have only owned this computer for 3 weeks before running into a serious issue already with my video card. Did I buy a lemon? I am not one to complain but I am now worried there might be other damage to other hardware. I want this computer to last a good 5 years problem free and in less than in a month so far I have to take it in for a possible new video card. Thank you for your input.