Testing MSI 790FX-GD70 with 4 x ATI Radeon HD 4890 and Phenom II X4 ES under LN2 didn't go that well

I prepared everything with air cooling. Graphics cards were running @ 980/1115 MHz with fans blowing full speed. 3DMark03 score was around 108500 with Phenom II X4 955 Black Edition @ 3,6 GHz & NB 2,7 GHz. I used Corsair DDR3-1800 memory @ ~860 MHZ 7-7-7-20 1T.



Then I switched to my Phenom II X4 ES CPU which I just recently tested with LN2 on Asus Crosshair III Formula @ 6,328 GHz (1,785 V). I insulated Socket AM3 area and mounted F1 EE pot on CPU and started cooling it down with LN2.

When temperature was around -120 Celsius I started adjusting some settings from BIOS. I set up clock speed to 5 GHz and raised vcore to 1,6V but when I saved the settings system would boot/post no matter what. I cleared the CMOS and system started immediately with default settings. Soon temperature had dropped to -190 Celsius and I was still struggling to boot/post the system.



Everytime I tried to change something from BIOS, three red leds turned on on graphics cards and debug-leds on mobo showed FF. Nothing happened from reset button. System just wouldn't boot/post but after clearing CMOS it started without issues. I even tried not to change any settings from bios but no luck.

I let the container warm up a little and around -170 Celsius the system suddenly started. I quickly adjusted voltages from BIOS and thought I could change everything else with AMD OverDrive from Windows. Well.. CPU @ 3,1 GHz, 1,75V core, 1,45V NB and 2,12V to DDR3 cause system to completely shut down during loading Vista and it never woke up again.



After I warmed up the CPU I removed heatsink from motherboard and noticed that one of the Dr. MOS chips had failed. Seems like 1,75V was way too much for GD70's PWM. I've been using even higher voltages (1,75 - 1,875 V) with Asus M4A79T Deluxe and Crosshair III Formula. With early samples we used +1,9V with Gigabyte 790GX and DFI 790FX boards.

The worst part is that of course motherboard took the CPU with it and both are now dead.

Be carefull with GD70 and extreme cooling / voltages