PSU Amperage confusion

[Powder37]

Hello All,

First i want to say that I've been researching / pricing out this build for the past couple of days, and in my searches this site has consistently been at the top of the list and always had the most relevant answers. This site and the people on it are awesome!

Anyway, it's been 5+ years since I've built a gaming computer, longer since I've built one from scratch. I'm pretty sure about the rest of the build, however there's one thing that's confusing me - and that's the PSU.

Specifically, I'm confused about the Amperage aspect of the PSU. I've used a Wattage calculator and I believe I have a good idea about the minimum wattage I'll need, however the amperage discussions floating around on the net just leave me confused and unsure about any of the PSUs I've looked at.

Specifically:
1) Where does the amperage come into play? i.e. video card(s), HDDs / SSDs, mobo power connectors, etc.
2) How do I determine what kind of amperage I need? What components determine the amps I'll need?
3) I'm Going with a Crossfire build, do I specifically need a Crossfire ready PSU, or is that just advertising gunk?
4) When someone says "Don't save money buying a cheap PSU!" ... what's considered cheap?

I'm considering the following 750w PSU:
http://www.newegg.com/Product/Product.aspx?Item=N82E16817139010

Here are the links to the build I'm considering:
a) Case: COOLER MASTER HAF 932f, http://www.newegg.com/Product/Product.aspx?Item=N82E16811119213
b) CPU: AMD FX-8150 Zambezi, http://www.newegg.com/Product/Product.aspx?Item=N82E16819103960
c) MOBO: GIGABYTE GA-990FXA-UD3 (AM3+, dual crossfire ready), http://www.newegg.com/Product/Product.aspx?Item=N82E16813128514
d) RAM: Corsair 4x4 gigs DDR3 http://www.newegg.com/Product/Product.aspx?Item=N82E16820145345
e) GPU: 1x (2x when needed in the future) Sapphire Radeon HD 6850 http://www.newegg.com/Product/Product.aspx?Item=N82E16814102959
f) SSD: 64GB, http://www.newegg.com/Product/Product.aspx?Item=N82E16820148441
g) HDD: 2x 1TB 7200RPM 32MB cache (RAID 1), http://www.newegg.com/Product/Product.aspx?Item=N82E16822152185

Comments on the build are also appreciated, as it's been a while since I've looked into any of this stuff, and I'm feeling a bit rusty. It's also my first time attempting a RAID setup as well.

Thanks!

 

[TheBigTroll]

amperage is how many electrons are flowing to your components each second. you have to check your video card amperage requirements before you pick power supplies. actually, the power supply yo picked out is pretty awesome. it will do with yor build or any future ones.

now to comment on your build
1: 16gbs of ram is overkill. 8gbs is enough
2: why not consider a 128gb ssd when it isnt that much more?
3: i recommend the 7000s series cards because they are just that much better( ex.7850 is a great choice)
4: i recommend a sata 6 drive because they are much faster than sata 3. a good one is a seagate barracuda 64mb 1tb. consider doing a raid 0 configuration for speed. you can just back up info on another drive

 

[Guest]

amps are watts divided by volts. if a GPU uses 240 watts of 12 volts then it is using 20 amps. (240/12=20)
online PSU calculators and manufacturer specs always over estimate what PSU is needed to compensate for unknown variables such as CPU and amount of RAM used along with the quality of PSU.

when you want to know the power consumption of a GPU; google for reviews that have benchmarks. most have total system power that includes the cpu, ram, chipset and hard drives. so do not think that 380 watts means JUST the grfx card!

for starting to understand about PSUs trying here:
Everything You Need to Know About Power Supplies
Power Supply Guides and UPS info

 

[Powder37]

amperage is how many electrons are flowing to your components each second. you have to check your video card amperage requirements before you pick power supplies. actually, the power supply yo picked out is pretty awesome. it will do with yor build or any future ones.

now to comment on your build
1: 16gbs of ram is overkill. 8gbs is enough
2: why not consider a 128gb ssd when it isnt that much more?
3: i recommend the 7000s series cards because they are just that much better( ex.7850 is a great choice)
4: i recommend a sata 6 drive because they are much faster than sata 3. a good one is a seagate barracuda 64mb 1tb. consider doing a raid 0 configuration for speed. you can just back up info on another drive

Thanks for the reply! I was originally considering the 64gb SSDs because I figured I'd only use it for the OS, photoshop and a few other intensive programs. Load times don't really bother me much in most video games. Now that I consider it, knocking off $50 from those 8 gigs of ram and putting them into the SSD would a bigger bang for the buck.

I also wanted to keep the overall cost of the build relatively low - not too much more than a grand. Some things, like the case and PSU I wanted to splurge on a little because those are things that can last through multiple builds.