Power Supplies: How Much Power Do You Need?

[[JiF]Gib]

from http://www.pcpower.com/technology/power_usage/" onclick="window.open(this.href);return false;

Component Requirement
AGP Video Card 30W - 50W
PCI Express Video 100W - 250W
Average PCI Card 5W - 10W
DVD/CD 20W - 30W
Hard Drive 15W - 30W
Case/CPU Fans 3W (ea.)
Motherboard (w/o CPU or RAM) 50W - 150W
RAM 15W per 1GB
Processor 80W - 140W

For overall power supply wattage, add the requirement for each device in your system, then multiply by 1.5. (The multiplier takes into account that today's systems draw disproportionally on the +12V output. Furthermore, power supplies are more efficient and reliable when loaded to 30% - 70% of maximum capacity.)

If you add all the maximumns up and do a PCI vid card these days thats around 750W. 750/.5 = 1500W power supply or better these days for a gamming rig. So thats what I am getting. Just make sure you have a 5 or more fans in a case these days and or water cooling because it will pump out some heat.

[[JiF]Mike]

After my recent build I'm starting to question those general power requirements of components listed on many sites. On my new pc I haven't seen it draw over 200W. This could easily be because I'm not taxing the system much, but I've been running every game with everything turned on. You definitely want a good power supply though, everything in the pc relies on it! I'm just not too convinced these wattage requirements are very accurate anymore. I used them for my build, so just be aware and don't go crazy! Go for quality over total wattage.

[[JiF]CowHide]

PSU Calculater to get an estimate on how much you need: http://extreme.outervision.com/psucalculatorlite.jsp

There are a lot of variables on a PSU:

The make of the PSU makes a big difference. You can get a 700 w crappy one and it will only use around maybe around 500 w efficiency or a good one (seagate, corsair etc.) and it will use a good percentage of that power. Also make sure its certified as "80 plus" bronze, silver or gold (quality psu).

There is the quad or single rail to consider as well. From what I gather there are some that say single is better and some who say quad is. The higher the number the better and more important then the actual wattage.

Also you have to take in account that pretty much all products over estimate how much psu power you need. That way it covers them from the people that have a crappy brand psu.

This site is good for getting a good look at how much a certain GPU uses as well as comparing it with other cards.

http://www.hwcompare.com/918/geforce-gt ... 850-512mb/

Also when looking at charts like these, they would represent a GPU running at full capacity.

Some other sites to throw in.

Heres a good one to site the comparable GPU's between ATI and NVIDIA too (Kind of old now but good for older cards) http://www.tomshardware.com/reviews/bes ... 879-7.html

CPU Chart: http://www.cpubenchmark.net/cpu_lookup. ... 40+3.33GHz

Another GPU comparison : http://www.gpureview.com/show_cards.php

[[JiF]Gib]

ah good to know mike & cow.

I knew about bronze, silver, gold rating for efficiency but didnt know they were overstating power requirements.

Thanks!

BTW at http://extreme.outervision.com/psucalculatorlite.jsp" onclick="window.open(this.href);return false; it tells me at least 615w for what Im building. I think a gold rated 1000w PS is going to be ideal since you don't want to put more than 70% load on your PS from what they say. That makes sense, just like a CPU, you don't want to ever go over 80% utilization on your cpus or its like going over a cliff(Im a DBA and we are always watching that metric daily on all our servers).

The recommended total Power Supply Wattage gives you a general idea on what to look for BUT it is NOT a crucial factor in power supply selection! Total Amperage Available on the +12V Rail(s) is the most important, followed by the +5V amperage and then the +3.3V amperage.

[[JiF]Mike]

I bought this 1020W power supply for my new build: http://www.newegg.com/Product/Product.a ... 6817194081" onclick="window.open(this.href);return false;

I've been very happy with it. Price has come down quite a bit since I bought it too.