Hello everyone! This post is a last resort after several hours of attempts at getting my 2006 Mac Pro (1,1) going again... So, my symptoms are, basically, as follow: I hadn't used the machine in about 2 weeks and when I turned it back on, it got stuck in the boot sequence on the white screen with the Apple logo and the spinning dashes or whatever it's called I powered the machine down and then turned it back on only to get no video output whatsoever the post "chimes" rang, but video didn't appear... Since the area this machine was kept in had become cold (30F), I turned the machine off and heated up the area overnight on day 2, I tried to boot the machine again and the video resumed, but it got stuck on the white screen again... After doing several pram resets and unplugging for several minutes, I tried to reboot and it still got stuck on the white screen again... I plugged in a usb snow leopard flash drive and used Option-Boot to choose my boot source after choosing the flash drive, it STILL got stuck on the white boot screen (after accessing the flash drive for a couple of minutes) Since the above, I've had all sorts of symptoms including several boot attempts where the video didn't show again, etc now it's in some weird mode where pressing the power button immediately powers it on and off (i.e. no need to press and hold) and I'm not seeing any video or other results at all (other than the "post" chime) This is a Snow Leopard machine, probably the first release since it hasn't been connected to the web for a while. It has something like 12gb of RAM. There are two hard drives installed... only one of them is a boot drive. It's connected to an HP IPS monitor via DVI...no other peripherals are connected except the stock Apple keyboard and mouse. Does anyone have any ideas? It seems to me that something fundamental must be seriously wrong, and it's probably not the hard drive or graphics card since the flash drive boot didn't work and the video did intermittently work as well... I'm thinking that it must be either a RAM failure or a more fundamental logic board or logic board component failure, but I'm open to suggestions for additional things to try since, at this point, it seems I don't have much to lose. Thanks in advance for your help!