Need Good Quality 500 w ATX/ PS2 PSU

Most PSUs are PS2 style, many just have their fan facing downwards and pulling air in from the case and pushing it out the back of the unit. The Seasonic S12II 520W unit has the same dimensions as you listed and will therefore fit in there fine. Its also a nice high quality unit that can do all its rated for plus a bit more if needed.
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

My understanding of it is ATX/PS2 PSUs is they are smaller 140 x 150 x 86mm (W x L x H) and standard PSUs are larger about 150*160*86 mm. The SeaSonic S12II is a nice PSu but it is designed to be installed in the bottom of the case w/ the fan pulling fresh air into the PSU while the antec earth ea500d green is designed to be mounted in the top of the case pushing air out of the case. Ideally, I'd like to find a modular PSU designed to mounted in the top of the case pushing hot air out.

http://www.newegg.com/ProductProduct.aspx?Item=N82E1681...

Why is a Active PFC PSU a good thing? Does active mean it only draws the current it needs?

Both unit's are designed in the same way, the fan is meant to draw air into the psu then exhaust that air out the back of the psu, wether a psu with a 120mm fan is used as part of the pc's cooling sytem or not is dependant on the case first and then the user's preference.
In a top mount case the positioning is obvious ( there were some exceptions, the CM 830 was top mount but also vented at the top to allow large fan psu installation in either direction )
If the bottom mount case is not vented to allow for intake , a large fan psu would be flipped to allow it to draw air from within the case, making it part of the cooling system.
Newegg is down , can't see your link, hunters suggestion is a better option than the Antec IMO.

I carefully reread your explanation and recommendation. The SeaSonic deserves another look. Is the fan always active or is it activated by heat in the case?
When I return home later today I'll research some more.
After the PSU upgrade I need the remove the HDD cage then mount the HDD in the vacant DVD bay. Why? the M/b power connector will not permit moving the HDD to another bay in the drive cage. besides the length of the Sapphire 6850 (9.5") and the 6870 (10.5") are too long for case unless the drive cage is removed.

At this point i don't want to upgrade the case.

Thanks

The fan is always on but it will slow down when its not needed so it wont be very loud most of the time.

Active PFC means that it can take just about any voltage as an input unlike the passive PFC units that have the switch on the back that controls the voltage doubler circuit, PFC itself doesnt affect a residential user but does help the power companies and all modern designs now use it. All power supplies will only draw as much current as they need, they are a constant voltage setup, as are the plugs in your house, as it needs to provide more power the system draws more current from it and it in turn draws more from the wall.

The measurements for the S12II are 140mm x 150mm x 86mm according to the seasonic site and its jonnyguru review. It will fit fine, and the way the mounting holes are set up is that on a top mount case it will always point its fan down and into the middle of the case to help exhaust hot air from the case.

I just read the johnnyguru review on the seasonic. For a 500w PSU I probably can't do any better unless i can find the same PSU w/ modular cables.

here is the link for the antec psu.
http://www.newegg.com/Product/Product.aspx?Item=17-371-...

here is a review of the antec
http://forums.guru3d.com/showthread.php?t=322679

Poof!

http://www.amazon.com/Seasonic-80Plus-M12II-520-BRONZE/...

that's very nice but unfortunately it's too big.

# Brand Name: Seasonic
# Model: M12II 520 BRONZE
# Item Height: 4 inches
# Item Length: 10.75 inches
# Item Width: 8 inches
****************************************
it needs to be
140 x 150 x 86mm (W x L x H)
(5.9" * 5.5 " * 3.4 ")

anybody know how high off the m/b a right angle sata connector is?
it'll need to fit under the video card.

Dont trust the measurements from amazon, they have them all wrong on there. The PSU cannot be 4 inches tall or it wont fit in the standard sized opening which is 86mm(~3.38 inches)

According to the seasonic site it is 160x150x86mm so its only .78 inches longer than your current one, check to see if you have an extra inch of space to fit it into, if so it will work
http://www.seasonic.com/product/pc_retail.jsp

The case chassis has a "pimple" bump limiting the length of the psu.
sorry