I am searching for an HP desktop or workstation with an Intel i5 or i7 processor that would support a "large" graphics card like an ATI Radeon 6850, which has two PCIe power inlets and which takes up two slots worth of PCI height (like most higher-powered graphics cards on the market today).
I tried an HP Compaq Elite 8200, which was a double-failure: its processor heatsink interferes with the card, and also its power supply has no PCIe power plugs at all.
No, this is not for gaming--it's for a professional environment where we need to support up to four digital monitors on Linux (basically we know which graphics cards we want, but HP's site does not make it at all easy to find a model which would fit them).