In my Dell XPS T550, I run a Celeron 1400 on a Lin-Lin FC-PGA2 adapter sitting atop a passive (no VRM) Asus slocket.
I set the jumpers on the Lin-Lin to request 1.4v, and the jumpers on the Asus slocket to passthrough the voltage request. The Dell/Intel motherboard seems more than happy to provide the 1.4v necessary for Tualatin CPUs.
The R450 is slightly older, but since your adapter has a built in VRM, it should work just fine--at least with Coppermine CPUs. Tualatin support will depend on the range of your adapter's VRM (can it get down to 1.5v?), and whether or not it will take FC-PGA2 chips.
Standard Def Rigs
Super P3: PIII-S @ 1.63 GHz/FSB155 | 2GB DDR-310 | 6800GT AGP | 500GB 7200 RPM
Super G4: 2x PowerPC 7455 @ 1.5 GHz | 2GB DDR-333 | 7800GS AGP | 300GB 10k RPM
Super G5: 4x PowerPC 970 @ 2.5 GHz | 16GB DDR2-533 | x1950XT PCIe | 512GB SSD