I have an Gigabyte Radeon HD7770 1GB card. It works just fine, but I have noticed an issue where memory size detected differs from the actual size. For example dxdiag (both32 and 64bit) detects only 700MB. So does Can You run it (from time to time). I did validation with GPU-z and it does show proper size at 1GB: http://www.techpowerup.com/gpuz/9p6wr/ I am wondering whether this might be due to a faulty card or (crossed fingers) nothing to worry about. I love this card and it would, obviously, really blow if it's defective. Almost forgot to add that I am, currently, running on Windows 7 64Bit Home Premium. Windows 8 Pro 64Bit show the card as having 768MB of memory.