I have a Sapphire Toxic HD 4850 512mb from Newegg. I replaced an Nvidia 7800GT with it. I experience random crashes in a wide variety of games; the screen blanks out, monitor goes to no signal mode, computer freezes and the last half second of audio loops. Only way out of this is a hard reboot. I will detail all of the things I have tried and give my system specs below. I am looking for someone else with a similar problem or any suggestions anyone can make to fix this. I am aware that a new BIOS has been released for the sapphire 4870 cards, but it will not be compatible with my card. I NEVER had any crashes with my Nvidia card. I am not bashing here, just providing a compare to rule out other parts. Troubleshooting: 600 watt PSU, tested rails, they push fine. Multiple memtests, no errors Scandisk/defragmentation of all hard drives Disabled antivirus / other scanning programs Safe mode cleaning of drivers, tried 8.7, 8.8, 8.9 beta and now using 8.9 Profile (the XML file) editing to force clocks to not swap between 2d/3d GPU/Memory is NOT overheating -- entire system is within temperature ranges RBE to set all cores at a constant clock speed with the highest voltage Changed all 3d settings in CCC to every possible combination. I seem to have the best luck with AAA off, VPU recover on (even though it doesn't work) force off vsync, allowing applications to control AA and sampling Loading GPU with Folding@home to keep it busy (seems to help) Different resolutions, windowed/fullscreen settings Games affected: Bioshock - Unplayable. 2-15 minutes into the game, randomly on any level, black screen freeze Civilization 4 Colonization - at any point, even sometimes on the menus World of Warcraft - This game runs the best, no crashes in windowed mode, maximized, can run two instances (of the game, multiboxing) just fine Call of Duty 4 - First game I played with card, played the whole game without a single crash, still does not crash. Inconsistancies: I was once able to play Bioshock for 8 hours with only one crash about halfway through. I have tried to reproduce the settings and can not get a similar experience. I was also once able to play Civ 4 Colonization for six hours without a single crash. The next day when I resumed playing, I crashed within minutes. WoW would occasionally crash when using the test realm client in windowed mode without maximizing it (removing the title bar, edges) Sometimes after changing some 3d settings, I will get a crash when just using applications (not gaming or video intensive). This crash is different -- it will VPU recover itself, and then tell me I need to restart because the display driver stopped responding I have thrice gotten a BSOD while not gaming that gave a Thread stuck in device driver error. I have attempted all of the troubleshooting related to that (namely, new drivers) and have been unable to fix all of my problems. System Specs: Windows XP Pro 32bit SP3 5g ram (i know it's overkill, memtested fine) Xfi Platinum Pentium D 2.8 I am at a loss for ideas here. I firmly do not think that the card is 'defective', only that this is a driver or GPU BIOS issue. I will be happy to provide additional information. I apologize for the length and unpretty formatting. Thank you to everyone who reads this.