Crash with vertical stripes\grey screen on HD4xxx and HD5xxx cards.
This has nothing to do with ram, it's not limited to Sapphire cards (as people with cards by virtually every manufacturers brand are experiancing this) It's not what motherboard your using, power supply or an overheating issue. It appears to happen more frequently on the Windows 7 operating system, (and even more-so on Win 7 x64), but people are reporting this problem on XP, XP x64, Vista, Vista x64, Win 7 and Win 7 x64. there are too many people with too many different configurations for this to be anything but faulty cards.
I have two different hard drives, one is running XP X64, the other Win 7 x64. (Both ran flawlessly with the HIS x1950pro that I replaced with the Sapphire HD5770.)
The only problems I have on XP, are random re-boots and internet explorer crashes and recovers pages frequently, and some games crash to the desktop like GTA IV, but no crashes with vertical lines or grey screen or anything requiring a hard re-boot.
The Win 7 hard drive on the other hand, crashes with vertical lines in 2d applications, game crashes and IE crashes that all require a hard re-boot. Sometimes I can leave my computer on for three days and no crashes, then go to watch a video on Youtube and crash with vertical lines. Other times it will crash just sitting at the desktop. I have tried every suggestion on the forums short of flashing the cards bios, or anything that might void my warranty.
These are just my experiences mind you, other people may be experiencing different things but they all result in crash with vertical lines.
The sheer amount of people along with the extremely diverse computer setups involved points to one thing... Bad cards.