z8 is nice, I know for sure,
the dual xenon server grade mobo, like my z600 works station has but HP made.
let me guess both boards never worked for you and you bought them on fleabay, and are DOA? that it, what is the story here.
Let me guess more, (no history at all)
you just put in a new CPU, xeon, ?
well if you did and
1: it is not support, it will do that.
2: or it needs flashed bios to support newer xeons.
3; no you can not run all xeon's made in this mobo ever.
first off put only one xeon the primary socket.
and only ram for just it.
then at ausu we site makes sure you are using the right xeons first.
the correct path is with working xeon, flash the bios.
then upgrade xeons last.
5500 series processor
Six-Core/Quad-Core Intel® Xeon® X5600 Series (130W)
Six-Core/Quad-Core/Dual Core Intel® Xeon® E5600/E5500 Series (80W)
Quad-Core Intel® Xeon® W5500 Series (130W)
Dual Core/Six-Core/Quad-Core Intel® Xeon® L5600/L5500 Series (60W/40W/38W)
Six-Core/Quad-Core Intel® Xeon® X5600/X5500 Series (95W)
here is the offical list.
newest BIOS is 1401
i bet yours is super old bios and not stated, or what xeons you have.
as you can see it is not trivial this topic.
it seems owning just 1
Dual-Core Intel Xeon E5502
as cheap as $5 60 on fleabay will allow flashing this mobo firmware, worst case.