MSI Turbostream PSU with 8800gt

[zenmastervex]

Searched the forum for a bit, and it seems to be the general opinion to buy a new PSU when you buy an 8800GT. I almost hate to ask yet another PSU question because this horse as been beat to death this month.... but I can't find any information on the 8800GT in regards to this particular power supply. Here's the short and skinny of my build:

AMD 64 x2 4200 (OC by 10%)
Motherboard: ASUS A8N32SLI Deluxe
Four RAM sticks, totaling 2GB
Two IDE drives, one SATA, two LED 120mm fans, one LED 80mm fan, one CD-R drive
No further expansion cards

My current PSU is an MSI Turbostream 450watt, purchased in March 2005. The +12v has 18amps, and other than whats on the side of the box, it's hard to tell anything else about it ("rails" must be a new thing, because there's no mention of it on this PSU). Not much information about it on the internet for some reason. I am planning on buying a Corsair 550w VX in 3-4 weeks, so this would be a temporary setup. Also, I calculated my power consumption with the online PSU calc tool, and it says I'll need 333w with the 8800gt installed. Also, the 12v wattage is listed as 192w, but I have not checked it with a multimeter.

Here is a link to my current PSU: MSI Turbostream 450w

I've already ordered the video card, and it's sitting in the UPS warehouse until January 2nd, when it's scheduled for delivery. The model is an ASUS 8800GT 512BM TOP with a factory processor speed of 700Mhz.

Anyway, here are my questions: If I intall with the 6x2 PCI express power plug from the PSU and it doesn't power up/work/fails/stalls/etc, do I have any other options? I have a lot more amps on the 5v (45A, to be exact), so can I use the 5v converter for 2 plugs to power it as opposed to the 12v (which only has 18A)? Is 18A enough to power the 8800gt?

Thanks for taking the time to respond, even though this topic has probably grown stale for the veterans here.

 

[WR2]

Your new 8800GT only takes 1 6 pin PCI-e power lead from the PSU.

The PCI-e graphics slot provides 75 watts all by itself and the PCI-e 6 pin power lead can provide another 75 watts. The 8800GT probably needs about 80-90 watts.
The 18amps of 12v power gives your system 216watts (18x12) which is pretty close to the calculated 192watts your system needs. That 18amps is for ALL your 12v reqmts, not just the GPU. Probably too close for comfort. I'd suggest shutting down 2 fans and 2 HDs during installation and testing. After getting stable operations you can add the fans & HDs back (one at a time) and check to see you're still running stable. Of course the GPU at idle sucks a lot less power than during 3D gaming. A temporary hiatus in 3D gaming would probably be the worst you'd have to put up with and still have all your hardware running.
For comparion the Corsair 550 will put out something like ~480watts of 12v power - easily more than double your current PSU.

 

[carver_g]

^ Excellent and thorough answer.

I agree- not enough 12v headroom for stable and safe operation.