I have a sony vaio pcv-rz 44g pc that I feel has a failing motherboard. The hard drive failed and the video card was failing showing garbled characters on the screen. I replaced the video card with an asus ah3450 with on board 512 mb ram. I also pulled the ram and cleaned the contact edges with isopropyl alcohol. A usb thumb drive was partitioned with swap space and a fat 32 partition for persistant storage while running the live disks. The pc needed several power up attempts before it would pass the post test. Most times, there would be a black screen or it would freeze at 'checking nvram'. After a successful post, the live disk booted and all seemed well until a random hard lockup that would need a power down to remedy. Now, I get the single beep that signals a post pass, then a second beep a few seconds later and a black screen. I also noted that the cpu fan runs, but not the rear exhaust cabinet fan nor the video card cooling fan. 5 and 12 volts from the power supply checks good. I salvaged the pc in the hope of using it as a game machine.

sirius57,

I admire your intentions to salvage this PC, but I really think you are flogging a dead horse.

It is an old, low powered machine which is totally unsuitable for gaming in any event.

Specs:
https://www.cnet.com/uk/products/son...-pcv-rz/specs/

Have you gone into BIOS settings and verify everything is set up? It almost sounds like the settings went to mobo default settings similar to what would happen on a lot of units when the coin cell battery is removed.
Also, check your ram modules again to ensure they are properly seated, isopropyl shouldn't hurt anything if allowed to dry thoroughly before adding power, could be a problem if the mobo was not drained as some motherboards hold power even after the power supply is disconnected. Usually pressing and holding down the power switch after power is disconnected drains the mobo.

I did find a loose memory module and reseated it and checked to make sure all connections, motherboard included were secure. I still get a blank screen using both the original nvidia and the asus video cards. The keyboard and optical mouse light up and ctrl-alt-delete reboots the pc. The rear exhaust fan and asus cooling fan do not run. I also swapped out the pc2700 memory with the same type. Earlier, I was able to get the box to boot and get into the bios settings by swapping the not so good card back in and after the bios change, put the asus back in. For some reason, I was unable to get to the bios with the asus card installed. The asus takes extra power from the power supply. I also tried pulling the power connector to both cd-rom drives to see if power was the problem during boot with no change noted.

I started by swapping the asus card into another box and the other box booted fine and the on-board gpu fan was running. I then took its exiting nvidia card and installed it into the sony box. To my surprise, it presented me with the bios splash screen informing me that the exhaust fan was not running. Both cpu and power supply fans run ok. I then went into the bios setup and had to reset everything from boot device priority to system time, etc. Then it booted a live cd. I am running a window fan to direct air to the open box and will check to see if the fan died or its something internal. I am relieved. It appears that boot failure was due to several factors. A good lesson for me. Thanks for the clues.