How can I see if RAM was failing after removing it from the Mac? I recently replaced some original 1GB RAM modules in my Mac Pro with 4GB ones. After a day or two of constant uptime, I attempted to reboot the machine which resulted in the power light blinking quickly (an indication that there is bad RAM). I removed the new RAM, replaced with the smaller modules that were there before and things were fine.

I have had bad RAM before as indicated by ECC failures in the System Information screens. However, before rebooting I didn't look at these screens so I don't have screenshot proof to send to the vendor that it is their modules at fault.

Is a RAM failure somewhere captured in the system logs?
No, normally RAM failures such as the one you describe cannot be captured in system logs.

You should RMA the RAM modules as usual.