I can't tell you if that memory matches your motherboard - I do not have enough information - but as a WAG I'd say it would work.
P55 is the intel chipset, not the model number of the motherboard. If the motherboard is Intel branded it would have a number like DP55WG, DP55WB, DP55KG, or similar. You can use software (like CPU-Z or Belerac Advisor) to get this info, but you need a working computer to do that. Your best bet is to carefully inspect the motherboard to find the BRAND and model number printed on it. There is no reason to assume it is an Intel branded motherboard.
Intel DP55KG Motherboard | Hardware Secrets
The discussion in this article regarding memory types certainly raises my eyebrows. Is it designed for DDR2 or DDR3? Come on people! That is why I think it is important to research this further to choose memory that has been tested and approved for this motherboard. That's why you need the model number.
When you find the model number go to the MANUFACTURER'S webpage for that motherboard and look for the QVL list. Then choose a RAM module from that list or match the specs
exactly.
DDR3 memory running at 1333 comes in 3 flavors: PC10600, PC10660, and PC10666 - and can come in two general voltages 1.5v and 1.65v. You must get sticks in the correct voltage for the motherboard.
You should be able to read this information on the RAM modules you have. That doesn't mean they are correct however (stranger things have happened with those kit packages) so do not skip the research part.
As for the power supply: There is no compatibility issue with power supplies other than size (ATX is the norm) and available connectors (for your installed devices), and the total power needs of your computer. But if you get (or borrow) a similar sized supply with all the right connections in the ATX size format it will work in yours and most everyone else computers.
I always recommend a supply with a single 12v rail unless you know exactly what you are doing. And with power supplies you are looking for maximum AMPS on each of the voltages (3.3, 5, and 12v). The amps are much more important than total wattage. That video card could pull 18 to 22 amps all by itself on the 12v rail. You are looking for, in terms of amps, the most bang for the buck.
To decide on a BRAND of power supply I suggest you make a new post in the Hardware forum and ask what brands are best. Lots of opinions but the same few brands always come up: Seasonic, Corsair, PC Power & Cooling, Thermaltake, etc.
Better yet just search the hardware forum - this question has been done to death!