Need PSU Advise

hello. i need advise to see if i need a more powerful psu. at the mo have a 550WAtt HEC (high-Quality Evolution
Commintment) PSU.

my specs at the moment are:

1X AMD Athlon black edtion 2.7 GHz Processor

1X GigaByte M61PME-S2

1X Maxtor HDD SATA

1X Pioneer IDE Disk drive

1X Nvidia 9800GT

1X Belkin FD9000 Wifi Reciever

My GPU is my main worry. my PSU holds a DualRail 12V. channel 1 is a 18A rail and channel 2 is a 17A rail.
a bloke at CEX told me i need atleast a 750Watt PSU to power a 9600GT PSU. i have a 9800GT so i wonder if my PC is getting fried. my CPU is running Fast with no glag. my GPU i processing crysis Warhead on high like a charm, only at 60*C. i'm 70% i'm alright i just want to feel 100% alright.

also i am going to buy a new SATA Diskdrive next week so i can have two IDE connection Free, so i would like to put two Extra IDE Harddisk to my PC. Will this take it to Far for 550Watts

^5 +1 what obsidian86 said.

The general rule of thumb is a high quality 500 to 550 watt power supply with sufficient current (amps) on the 12 volt rail(s) can easily power a system with any single video card made.

Technical reviews right here at Tom's Hardware, AnandTech, and Xbit Laboratories indicate that the total power draw at the wall outlet (mains) during a gaming session such as World of Warcarft for a moderately overclocked system with one video card is typically just a little bit under 300 watts. That is total power for all of the components. There are a few exceptions.

HuH!
I am running a 9800GT on a 400W PSU(Corsair) with EASE.

Thats more than sufficient.

A quick and dirty "rule of thumb" is to take 50%
of the rated wattage of any PSU, and make a
decision if that 50% will satisfy the system
you are planning to build.

This rule of thumb takes into account
PSU efficiency, single- v. multiple-rails,
probable future expansion, and a
subjective desire to avoid spending
too much time on this decision.

Thus, if you are considering a 550W PSU,
then the system you are building should
consume about 275 W.

As Dell discovered many years ago,
lots of systems can be powered reliably
with PSUs that are rated lower than what
the IT industry's marketing geniuses urge
upon us: that's because PSU makers
enjoy huge profit margins on their larger PSUs.

The next level of analysis should take
into consideration the rated efficiency
of any PSU, at an average 50% utilization.

Statistically, most PSUs will experience
maximum effiency at or near 50% utilization --
which is another common sense reason
for our "rule of thumb".

So, compare 500W @ 80% with 450W at 89%.
Even though the latter may cost somewhat more,
the former was probably built with inferior components.

Also, a more efficient PSU will waste less energy,
over time, and the whole planet will benefit
as more people buy power-efficient electronics.

The next level of analysis takes into account
single- versus multiple-rails, modular versus
non-modular cables, and other considerations
such as the space available in your chassis:
some PSUs impinge on fan grills in the bottom
panel.

BEST WAY is to start planning early, then
to look for sales, free shipping and such,
on one or more of your preferred selections.

Newegg, for example, has a feature which
permits you to receive an email notice
if/when the price for any given product
goes below a user-specified threshold.

It's probably a good idea to install your PSU early
e.g. first when assembling your system,
in order to plan and implement cable routing
to effect maximum air flow. This is another
reason to get your research done early.

Hope this helps.

MRFS

the 550 will be fine drives aren't as power hungry

The entire post is way to much to include in the quote, but very well put.