Hello. I have an old system based on 939 socket. It is an Athlon 64 2800+ on a gigabyte mobo with two gigs of ram. And now the problem. Before buying the new Sapphire 5770 I had a 6600 GT video card. I bought the new card and a new PSU thinking that the old one should be too slim for my purposes - it is a Maxcube Real 500W - Nira, ATX rev. 2.3, PFC Passive, 120mm fan, 20+4pin M/B x1, 8pin/4pin+12V CPU x1, 6 pin/6+2 pin PCI-e x1 , Peripheral x5, Floppy x1, SATA x5 with the following specs : ATX v2.3 1 x 120mm +3.3V - 22A +5V - 16A +12V1 - 15A +12V1 - 16A +5Vsb - 2.5A 1 x 24pin 1 x 8pin 1 x 8pin PCIe 5 x SATA 5 x 4pin MOLEX 1 x floppy So i installed the new PSU and the new cad pressed the power button and the the system started to boot but with no response form the monitor. I tried to remove the PCIe-AUX power connector to see if there will be any error beeps but nothing happened. The monitor remained blank. I put the old card back in the system and it worked perfectly. I took my new card with me at work and put it on an office pc with a ridiculous 300 W PSU ant it worked just fine. At home it spins the cooler but nothing else happened. I tried to put my old card on the primary PSI-e slot with the 5770 on the second one but after booting the system could not see the secondary card (everest, cpuz). Any ideas? The Mobo is fine, both cards are fine, the psu , i think, is powerful enough...what do you think? Thank you in advance.