Q: can i just replace my 305w dell psu with a 600w psu
A: yes, they all have mostly the same or the sockets that you would require. but extra sockets that you would have to check if they have are: 4/8 pin (which is for the motherboard, and connects to the 4 pin connection, some motherboards have a 8 pin instead, and the PSU will come with a 8 pin that can change into 2 4pin connectors) PCIE - some come with 1 or more 8 pin PCI-E some come with 1 or more 6 pin PCI-E and some come with 1 or more 6/8 pin PCI-E 20/24 PIN connection - some PSU's come with a 24 pin connection that goes strait into the motherboard, and if you only have a 20 pin connection ont he mobo, 4 pins will slide off. Sata - some don't come with a dedicated Sata connection. standard with all are: 4 pin molex 4 pin motherboard 20 pin motherboard 4 pin floppy connection but knowing Dell they sometimes make there own connections and you have to get a dell specific. (or so i've been told) i've never bought a dell machine! and never will! EDIT_ there are some differences. and thats in size. micro ATX and ATX, (think theres one or 2 more) check what it says on yours, and check the measurements. if you dont know yourself ask someone, or post a picture of it on hear and someone will tell you. but i'm sure it's a standard size.