yes, your serial no. works.
Why doesn't mine?
Of course I have the same mainboard, but probably a different Bios version, 'cause there is an option to select the primary video output.
But still it's an OEM Fujitsu-Siemens Bios. You can see it on the splash screen during Bios' post.
As for the HD3450, actually PCIe 2.0 is backwards compatible, but there are sometimes problems though.
You could also try to enable "PEG Force X1" in the "Advanced Chipset Features".
Or at least just boot through the onboard VGA with the Radeon plugged in, install the drivers in Windows and set it as the 1st video device.
In that case you wouldn't see the Bios during booting, but Windows would work with the card.
I've read you previous posts once more, and the thing is I just don't noticed the high temperature at first.
The E6600 has the same TDP as the E6320, so there shouldn't be such a big difference.
Arctic Silver has a very good instruction
on how to apply the thermal compound to Intel's Dual Core CPUs.
Perhaps that helps.
Many users spread the compound over the whole heatspreader. Don't do this. It was only necessary with older CPUs without heatspreader to spread the compound over the exposed core.
I don't know Maplin very well, because I live in Germany. We don't have it here.
But since at least Siemens is a German manufacturer, FSC is a common brand down here. Especially the "Deutschland-PC" (which means "German PC") series is very popular. I just don't know why. The machines aren't that good.
In fact the Fujitsu Siemens joint venture ends on March 31st. So there won't be FSC in the near future any more...