PSU help: HX620W vs. ST75F vs. ST75ZF vs. M12 SS-700HM

[Zork]

I’m in the market for a new PSU for a new system build. I want a PSU that will support nextgen DX10 video cards (i.e., Nvidia 8800GTX or equivalent) in SLI/CrossFire. If possible, for expense reasons, I would like to stay within the 600 – 750 watt range (is this realistic/doable? I read an article (theinquirer.net/default.aspx?article=36066) that suggests a 700+ watt PSU isn’t necessary for nextgen DX10 video cards in SLI -- anyone have any comments/thoughts on that?)

What I need to know is will any of these PSUs (listed below) fit the bill (even though they don't “officially” support nextgen Nvidia 8800GTX video cards in SLI)? If so, which do you recommend and why? If not, what other PSUs do you recommend?

Corsair HX620W (620watt) newegg.com (http://www.newegg.com/Product/Product.asp?Item=N82E16817139002), zipzoomfly.com (http://www.zipzoomfly.com/jsp/ProductDetail.jsp?ProductCode=373110)
Silverstone ST75F (750watt) newegg.com (http://www.newegg.com/Product/Product.asp?Item=N82E16817256009), zipzoomfly.com (http://www.zipzoomfly.com/jsp/ProductDetail.jsp?ProductCode=267004)
Silverstone ST75ZF (750watt) newegg.com (http://www.newegg.com/Product/Product.asp?Item=N82E16817256006), zipzoomfly.com (http://www.zipzoomfly.com/jsp/ProductDetail.jsp?ProductCode=267008)
SeaSonic M12 SS-700HM (700watt) newegg.com (http://www.newegg.com/Product/Product.asp?Item=N82E16817151031)

I’m leading toward the Corsair HX620W because of its price, features, and its quality/performance (it has received very excellent reviews). Plus, I read a article (http://www.pcstats.com/articleview.cfm?articleID=2035) that said “While the [Corsair HX620W] PSU does not officially support nVIDIA's GeForce 8800GTX in SLI, since the HX620W only has two PCI Express videocard connectors, I don't think it would have any problem powering that beast should you use a couple of molex to six pin converters” (Anyone have any thoughts on this?).

That being said, the others have all gotten good reviews too and they have more watts –- I also believe they have four 12V rails (as apposed to three like the Corsair). Are any of the differences between these PSUs significant? Do I need more watts or 12V rails? Additionally, between the two 700 watt Silverstones, is there a significant difference in quality/performance? Is one better than the other? The ST75F is more appealing because it's cheaper and has modular cables (the ST75ZF doesn't), but it doesn't "officially" support SLI (the ST75ZF does).

Also, regarding PSUs with fans on top (and not on the back), will such PSUs (such as the Corsair) work in the case I ordered (ThermalTake VC3000BNS (http://www.thermaltakeusa.com/product/Chassis/midtower/armorjr/vc3000bns.asp))? The case doesn’t have a top vent, does that matter? (Sorry if that’s a newb question!)

Thanks in advance for any help/info given!!!

[Oklahoma Wolf]

The Silverstone ST75ZF is the best built of those being a server grade unit, but the Corsair and Seasonic are no slouches themselves. The ST75F is the only one of the four that has left me a bit underwhelmed... you should be just fine with one of the other three.

[Zork]

Hi Oklahoma Wolf, thanks for your quick reply!!!

When you say I “should be fine with the other three,” are you referring to the ability to run two 8800GTXs in SLI, such as with a couple of molex to six pin converters? Can you clarify? I want to make sure I understand you correctly.

Out of the Corsair and Seasonic, which do you prefer and why?

Also, do you mind elaborating on why the ST75F has left you underwhelmed?

[CAD4466HK]

Not to come off sounding like a CAD:p
But IMAO, I suggest doing a little more research on your query;)

http://www.jonnyguru.com/reviews.php

[Oklahoma Wolf]

When you say I “should be fine with the other three,” are you referring to the ability to run two 8800GTXs in SLI, such as with a couple of molex to six pin converters? Can you clarify? I want to make sure I understand you correctly.

I mean they can all run those cards in SLI ;)

Between the Corsair and Seasonic I actually prefer the Corsair, though since Seasonic makes them both it's really hard to pick a favorite. I like the cabling on the Corsair.

The ST75F is based on the same Enhance unit as the ST65ZF and ST60F - jonnyGURU's review has left me with the impression that design is running out of gas.