I apologize in advance for what may be a redundant question. I searched for this precise scenario, and read the GPU/PSU thread, but I'm poor and spending a great deal of money, so I'd like to hear first-hand from somebody with a bit more experience than myself. I'm rather skilled/versed in building computers, but my experience is limited in the sense that I've always stayed rather safe within the confines of the "average" PC. I haven't had the chance to venture out into high-end hardware, so this is a first for me.
The GTX 480 claims it needs "Minimum of a 600 Watt power supply. (Minimum recommended power supply with +12 Volt current rating of 42 Amps.)"
I obviously have the minimum 600w requirement met, and I also need a 12 volt rail with a current rating of 42 amps.
My understanding of the required amperage is that as long as the TOTAL exceeds the recommended rating of 42 amps that all will be golden.
I.E.: my 22A, 22A and 25A rails equal 69 total amps, and I'll be fine.
I will not/have not be/been overclocking my GPU or CPU, and I have an Antec nine hundred two case with exceptional airflow and a side 120mm fan installed, so I don't think heat from the stock GPU/PSU will be an issue. I will only be running one GPU. If necessary, I'm running an Intel Core firstname.lastname@example.org, with 8gb of Corsair XMS3 DDR3 RAM and a WD Caviar Black 7200 RPM HDD.
After digging around a bit more, I found a few things.
A chart listing power supplies and their amp ratings, etc. It stated that the EA650 was rated at 45A, which is slightly above what I need. I'm still curious as to why it's listed at 45A, though.
Then, I found:
43-54 amps - Often "650W" PSUs
This range is a good choice for the gamer with two moderate video cards or one very high power card. Start adding in a lot of hard drives, fans, water-cooling... and you might be more comfortable in the next range, especially with moderate overclocks of the CPU and GPU(s)
This basically puts my mind at ease, but I'd still love a response confirming that my system will be working properly.
You can't add the rails together. 22+22+25 might equal 69, but the thing feeding those three rails can't supply full power to each of them. You know it HAS to be false because 69A x 12V = 828W, which is way more then the 650W PSU is rated for. If you read your label on the PSU it should say something about 12v1 + 12v2 + 12v3 not to exceed XXX watts. Divide that number by 12 to see how many Amps a PSU can output AT ONCE ON ALL 12V RAILS.
Yes, thats the line you need to pay attention to. As long as you don't plug in more then 45A worth of stuff you'll be fine. A single GTX480 will work ok, two is obviously out. I think you need close to 60A for that.