Dell Dimension 5150/E510

[DeathBringer]

When I try and boot the Core 2 Duo (E6750) or the Pentium D (E2140)

E2140 isn't Pentium D.
Try to boot with real Pentium D - http://www.cpu-world.com/CPUs/Pentium_D/index.html

I have attached the screenshots

Press button Preview Post and attach files.

[TheDood]

I see, that explains my confusion as everywhere says it should boot with a Pentium D. I don't own one, should I track one down? I'm a technician so there may be one at work if I'm lucky.

[TheDood]

That's what I've been doing, try this mate. Sorry about that
https://i.ibb.co/2kqdvgm/chipset.png
https://i.ibb.co/XDQS8W1/cpuid.png

[DeathBringer]

This motherboard hasn't support for Conroe core. It's VRM's incompatibility.

[TheDood]

That's what I was thinking myself after the research I did. But my methodology was if you can run a Pentium D why can't you run a Core 2 Duo? The Pentium D was a power hungry toaster! Core 2 Duo's were much more efficient. I'm no expert in this area, but thanks for the help man! Appreciate it