I was considering purchasing a new pair of Intel Xeon 7340s for my PowerEdge 1800. I currently have a single core Nocona in it. How do I tell if the new CPUs are compatible and if the motherboard will take it?
As far as I've ever seen/heard, only Irwindale and Nocona processors are supported. So, it is very unlikely that your system will take 7340's.
Here is a list of supported processors for the Intel chipset in the 1800, although some may not be supported by the Dell BIOS:
You can call Dell support in the States/Canada for free - for any problem or question - regardless of warranty status - they could give you a full list of supported processors.