Hi, I have a 7600GT video card and i want to buy a 8800GTX video card. The only problem is, I have a 500W power supply and the 8800 need a 475. Do i need to buy a 600W power supply or is it ok to run the card anyway?

Its not about watts, Its all about Amps on the single 12v rail PSUs. A PSU like a OCZ Powerstream 520w has 33Amps on a single rail. Which is enough for a 8800GTX and is at a good price.

OCZ OCZ520ADJSLI PowerStream 520W Power Supply Retail at ZipZoomfly

The 8800GTX recommends 30A or higher, this PSU will work great. Mines running a overclocked 8800GTX and overclocked X6800 with out a problem

Ok Thx. My power supply is 30A, that means like you said that its quite enought to run a 8800GTx, i don't want to overclock it anyway so its perfect.

I have a Tagan Dual Engine 600w TG600 u25 PSU.

Looking on the box, there is a table that says:


DC Output Max. Output Current

+12V1 = 20A |
+12V2 = 20A | 48A
+12V3 = 20A |
+12V4 = 20A |

+3.3 | 28A
+5 | 28A
-12V | 0.8A
+5Vsb |3.0A


Does that mean I have 48A on a single rail? or 20A through each PCI-E cable up to a total of 48A across all four rails?

Can someone confirm if my PSU is enough?

I've been using it with my 8800GTX for about 5 months with no problems, and my FPS rates matching all reviews. Never had a single PSU related problem so it must be getting enough power, right?

"For a single board, Nvidia recommends a 450W or better power supply with a 12V current rating of 30A. The 8800 GTS needs a 400W PSU with a 12V current rating of 26A. These are well within norms for modern PSUs. Of course, if you plan on running multiple RAID arrays, a pair of 8800 GTX cards along with a heavily overclocked CPU, you will need a beefy power supply."

Well if it's well within the norms, my Tagan Dual Engine 600w is one of the more expensive in the 600w region and certainly above 400w...

It means you have 20A Mr Fiddles. Now, the good news is that cards like the 8800GTX have two power connectors, so you could use it with that PSU as long as you made sure that the connectors were on two different 12v Rails.

When they started coming out with PSUs with multiple rails I thought it was great, more power. Then I realized that much of that power gets wasted. Singe 12v Rail is the way to go.

How do I know if they're on two different 12V rails?

There are only 2 PCI-E power cables on the PSU, both running into the 8800GTX so I have no choice...

Basically, so long as each cable is on a different rail (listed as 20A each rail), then I have 40A to play with, right?

"The conclusion is simple. 25-27A on the +12V lines for a single 8800 is more than enough. And in case you need a SLI configuration, make sure you have at least a 30-34A capable PSU. Note that not all PSUs run according to their specification and current on the +12V line may be lower in reality. In order to stay away from trouble, a good quality 430W-480W from a top manufacturer should be enough."

So I got myself a 600w PSU that cost me £90 and it supposedly isn't enough for ONE 8800? I find that hard to believe especially as it's been running immaculately for months.

Also, I asked Tagan directly and they assured me it was more than enough for a single 8800GTX.

Well, if Tagan was smart, and I assume they are, the two PCI express power connectors are on 2 different rails, giving you the 40A you stated. And since it is working fine, I think it is safe to assume that is the case.