What wrong with more power in your power supply?


Mar 21, 2009
I have a question about power supplies. I actually need an answer rather quickly because the sale will run out. This may seem like a dumb question but I would always rather have too much power then be on the border and maybe not have enough.

I know in my current build I am doing that I probably only need 400-450 watts of power for my system to run efficiently. I am currently planning on putting in a 550 watt PS. Right before I was going to purchase it, I see a very good deal on a 850 watt power supply for only $10 more which to me to get more power and maybe a better PS would seem like a no brainer.

My question then is what would it matter to get the bigger PS? Is it just power consumption, weight, etc. or is their a reason everyone seems to put the bare minimum of power in their build.?

Note: I dont plan on adding a video card for a long time if ever, and I am not sure I will ever need the extra power in this build but I just thought a better PS may be good. Games will not be played on it.

Here are the 5 PS I was looking at. I can get the highest PS for $59.99, with the rest being $49.99 or less. The 430W will be $24.99 after rebates. I just am not sure I want to be on the edge with power with the 430W.


Here is my build.

ASUS DRW-24B1ST/BLK/B/AS Black SATA 24X DVD Burner - Bulk - OEM
http://www.newegg.com/Product/Prod [...] 6827135204

Antec Three Hundred Black Steel ATX Mid Tower Computer Case
http://www.newegg.com/Product/Prod [...] 6811129042

2 Drives to make a RAID to back up work.
Western Digital Caviar Black WD1001FALS 1TB 7200 RPM SATA 3.0Gb/s 3.5" Internal Hard Drive -Bare Drive
http://www.newegg.com/Product/Prod [...] 6822136284

Logitech MK520 USB RF Wireless Ergonomic Desktop
http://www.newegg.com/Product/Prod [...] 6823126192

AFT PRO-35U All-in-one USB 2.0 Card Reader

ASUS P8Z68-V PRO LGA 1155 Intel Z68 HDMI SATA 6Gb/s USB 3.0 ATX Intel Motherboard with UEFI BIOS
http://www.newegg.com/Product/Prod [...] 6813131730

Intel Core i5-2500K Sandy Bridge 3.3GHz (3.7GHz Turbo Boost) LGA 1155 95W Quad-Core Desktop Processor BX80623I52500K
http://www.newegg.com/Product/Prod [...] 6819115072

Crucial M4 CT128M4SSD2CCA 2.5" 128GB SATA III MLC Internal Solid State Drive (SSD)
http://www.newegg.com/Product/Prod [...] 6820148448

Will buy 2 of these for a total of 8GB.
G.SKILL Ripjaws Series 4GB 240-Pin DDR3 SDRAM DDR3 1600 (PC3 12800) Desktop Memory Model F3-12800CL9S-4GBRL
http://www.newegg.com/Product/Prod [...] 6820231313

Any and all help would be appreciated.


Hi there, welcome to the forums.

You ask an intelligent question. If more isn't better, why not?
My personal reasoning is efficiency. Power supplies run best at around 50% efficiency. So, you want to find a PSU that gives double what you think the system will pull.

For you, the best bet is the Antec 430 in my opinion. It's 80+ bronze, of better make than the Corsair, and supplies just the right wattage.

In a system, the biggest draw is usually the video card. Since you don't have one, I would not expect this system to crack 150w ever. That means the 430w is just about right!
The reason most people tend to opt for one of the smallest units they can power their system with is usually price, but when there is a larger unit for only a tiny bit more than the smaller cheaper unit is not a bad idea to grab that one instead for the future. While it is true that computer power supplies are most efficient between 50% and 80% load, and decrease in efficiency at low load, that doesnt mean they are horribly inefficient at low load. In the review of the HCG 750 at HW secrets at 150W load it was only down to 84% efficient so it would still be reasonably efficiency when your system was at idle, possibly more so than the 500CX or 430CX.

It is true that big units are less efficient at lower loads than a smaller unit, but that smaller unit needs to be of similar design and have similar peak efficiency, a gold rated 750W unit is likely to be more efficiency at 100W than a bronze rated 400W unit because its curve needs to peak higher.

With no dedicated graphics card in that system the 430CX would be more than enough but if you do have intentions of adding on in the future then it would be worth it to invest in the stronger unit.


Mar 21, 2009
Thanks for all your help guys. I decided to go with the Antec BP550. Good reviews so I hope it works good. May be a little over kill but if I add a video card someday I will be glad to have it.