I am going to build a new rig soon, and I am going to need a new power supply. My new rig will be:

Intel Core 2 Duo e8400
2x1GB DDR2-800 (will eventually add 4 sticks total)
Nvidia GeForce 7900 GS (I will upgrade to an 8800GT aswell)
2x120MM standard case fans
1x140MM LED case fan
1 IDE 120GB HDD + 160GB SATA2 HDD
1 Lightscribe DVD+/-RW Drive

I used the eXtreme Power Supply Calculator at http://www.extreme.outervision.com/PSUEngine
and got a tiny 274-Watts. Then I went to Newegg's Power Supply calculator, plugged in the same stuff and got 510-Watts. There is a bit of a difference between the two, and I don't know which one i should trust. Can anyone help me out here? I am not a overclocker either, everything in my system will be stock.

Your system will never draw much more than 300W even with the upgrades. Power supplies are generally most efficient at around 50-60% load. Look for a quality 450-550W model such as the CORSAIR VX450.

The difference between most efficient and least efficient load is 2-3% on quality 400w-500w 80+ models.

Newegg's PSU calculator is even worse than Outervision.

Most good PSUs are at their most efficient between 70% - 90% load. A PSU with that is certified as "80PLUS" will be at least 80% efficient

The Corsair VX450 (made by Seasonic) will be fine even after the upgrade.


Newegg's crappy PSU calc said my PC requires 552w. Pure BS especially since I "only" have a 500w Seasonic S12 PSU. Then again, they are trying to cover their ass, they over recommend the minimum PSU so that people will not sue them (lawsuits seem like a popular sport in the USA) if their PCs crap out because of too little power.

Hmm, if that's the case, then could I still use the power supply that I used to power my old rig? It is this item: http://www.newegg.com/product/prod [...] 6817182022
I'm using it right now in my current rig (in sig) and it seems to be working fine. It says that it's only >65% efficient though.

What about this one? http://www.newegg.com/product/prod [...] 6817182030
It claims that it's over 72% efficient, has good ratings, looks cool, has plenty of power, and is cheap. Do you think i should just buy that when I get an 8800GT at the end of the year? Or not at all? Thanks for your assistance.

There is a reason Rosewill power supplies are so cheap. Go with the Corsair VX450 that I linked above. You won't regret it.

Maybe I will go with that, but not right now. Perhaps when I upgrade to a 8800GT. Now my main question is: will my current power supply be suffice?

I would love to tell you yes, but I don't want to be responsible if your system fries. If you are looking for something cheap that will get you by even if you upgrade to the 8800GT check this out:
Antec earthwatts EA430

I have found this article http://en.wikipedia.org/wiki/Computer_power_supply helps people who have questions about the size of power supply needed for DIY personal computers.

If I were you I would be looking for a power supply that meets the ATX12V 2.2 and EPS12V standards. Power supplies the standards mentioned begin with power ratings of 550W.

It was previously mentioned, for your power supply to run efficently it needs to have a load of 40 to 60% of the rated total power output.

How about this one? Would it last for future upgrades aswell? Like an 8800 GT or better, more RAM, hard drives, etc? It's way more expensive then I would like :| http://www.newegg.com/Product/Prod [...] 6817151040
Also, why is Rosewill so bad? They have the highest ratings on newegg, much higher then most other company's power supplies. I believe you in saying that the 80 PLUS and Seasonic power supplies are way better, but I just want to know why.

Check out jonnyguru.com, I'm not sure which ones, but he has given his blessing to a couple of Rosewill PSU's. Don't go strictly by Newegg ratings and customer reviews and don't 'put a price' on your power supply, you can set a budget but don't say 'I'm not spending over $X amount. Systems need stable, clean power output, especially when you start adding GPU's that need power and you start overclocking, which leads to overvolting, if you will. A difference of say $20 may get you something better. A couple of weeks ago, buy.com had the Corsair VX550 for $50 after rebate and google checkout and that was a steal. This is just as good a deal on the HX 520 that's modular.
http://www.buy.com/prod/Corsair-VX [...] 66485.html

I myself chose a 600W PSU knowing it was more than I needed today, because it would allow me to connect two video cards and power what I was running in the future. It may be a better idea to get the biggest PSU that you can comfortably afford... that way buying some security for the future too. They are cheap to begin with and nothing worse than having to spend double the money in the end to get two different PSU when could have bought one in the beginning that was good enough for future expansion. Good to also look for a long warrenty term too... mine was three years.