Three 12V lines at 18A

[joeflint82]

I have a PSU that has 12V1@18A, 12V2@18A & 12V3@18A. I have been using a GeForce 8800 GT without issue for a while now, but I have been looking to upgrade recently, and have been doing a bit of research. I came across a site that suggests for a lot of the cards that I am looking at that I would need a 12V line at 24A, which is also what my current card apparently requires. How does it work with my three lines? If I am only using one, can my card have accesss to the other 36A's on the other lines? (The potential upgrade cards I am considering are 460/560, probably from eBay).

The most graphically dependent game I have ever ran on my current setup is Sid Meier's Railroads, it runs smooth on 4AA and medium settings, but jittery on 8AA max settings (@1680x1050 my max monitor res), basically I'd like to run that game on full whack on my current monitor, and I would like to start playing other games such as BioShock 1.

I have recently bought a Core 2 Quad Q6600 to replace a Core 2 Duo E6750, but it hasn't been delivered yet. My motherboard was bundled with a Medion and I know it does not support CPU overclocking, ut could I overclock my graphics card?. Nothing in my system is overclocked.

I am in the UK. Thanks for any advice.

Edit:
My PSU is an Arctic 500W, I would prefer to avoid the expense of a new one.

For example, this is info about a 460 GTX
http://www.nvidia.co.uk/object/product-geforce-gtx-460-uk.html
Thermal and Power Specs:
Maximum GPU Tempurature (in C): 104 C
Maximum Graphics Card Power (W): 160 W
Minimum System Power Requirement (W): 450 W
Supplementary Power Connectors: 6-pin & 6-pin - Does this part indicate it uses two lines?

I am considering a bid on this item http://www.ebay.co.uk/itm/261133220379?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649

 

[cuecuemore]

What model PSU is it? If you've been running an 8800 GT without issue you're most likely good to go on a newer midrange card.

 

[weaselman]

It depends on how the PSU deals with the 12v rails, the two types are Independant, and combined.
Independant will provide say 18A for example to each 12v rail at a max, where as a combined rail 12v rail setup will be able to switch how many amps are required on a rail by taking some off the others to balance the Amp draw. A good quality PSU is a must so dont skimp on it, make sure you buy a well known branded name of PSU.

 

[joeflint82]

My PSU is an Arctic 500W, I would prefer to avoid the expense of a new one. I have edited my first post with some more info.

 

[joeflint82]

This is the site I am referencing:
http://forum-en.msi.com/faq/article/printer/power-requirements-for-graphics-cards
GeForce GTX 460 - 26A and a 450W PSU minimum
GeForce 8800 GT - 26A and a 450W PSU minimum

 

[joeflint82]

Update:
I have reluctantly conceded that I need a new PSU. I have won an eBay auction for a PNY GTX 460 Enthusiast Edition http://www3.pny.com/GTX-460-OVERCLOCKED-1024MB-PCIe-P2899C434.aspx

I would love advce for a new PSU, should I start a new thread?

My system is going to be:
Mobo: MSI MS-7358 Medion (I recognise this as a weakness)
Intel Core 2 Quad Q6600
PNY GTX 460 Enthusiast Edition
4Gb DDR2 800Mhz
500Gb + 300Gb SATA HDDs
2x DVD R/Ws
3x 120mm Case fans

Future plans: I am unlikely to ugrade again for a least 2ys, and I would only look to upgrade to a Intel i5, I wouldn't upgrade the graphics card, and am unikely to ever want to run multiple graphics cards.