7900 GTX 512 PSU issues for Gen 3?

considering the 7900GTX consumes less power than the 7800GTX, I know it will work fine.

The problem is the CPU which is bottlenecking it, and that is a fact. And the 460W rating of the XPS Gen 3 is most likely the average rating, not the max rating. 8400 is rated at "350W" while max is 460W, I have an X1800XL in mine and it runs 100% fine and to it's usual performance and speed, but the P4 560 chip I have bottlenecks it a good deal, that is a fact I knew before I got the card and you can test it yourself by comparing P4 X1800XL scores in 3DMark or games to A64 Processors in 3DMark/games. You'll see that my system is near top of the class for a P4 with an X1800XL compared to other P4 systems and that the A64s score higher by default and can score much higher than the P4 system ever can.

..."considering the 7900GTX consumes less power than the 7800GTX, I know it will work fine."...

No offense, but "I know" hardly qualifies as factual data. Unless you can provide verifiable Dell-stated data (which even the forum moderator can't get from Dell engineering http://forums.us.dell.com/supportforums/board/message?board.id=xps_desk_genhdw&message.id=8400#M8400 ) that the 460W power supply 12v bus amperage rating is 30 amps or higher, advising someone to go ahead and spend upwards of $500 on a video card based on personal opinion that it will work is, at best, a disservice. 

Message Edited by VCraig on 03-17-2006 07:09 PM

And here: http://www.guru3d.com/article/Videocards/326/4/

With compliments to mfh6375 in another thread, this is the tech spec for the 460W power supply - and in particular the 12v bus amp rating:

 I got it by opening the case and looking at the sticker. 17 amps on each of the two +12v rails equals 34. It is kind of a pain, though. The sticker was partially hidden, so I had to detach psu from case to get a good view.

Here is what was on the sticker(I saved specs in wordpad so I wouldnt forget):

+5v= 35 0A
+12v_A= 17 0A
+5vfp= 2 0A
+12_B= 17 0A
-12v= 0.8 A
+3.3v= 40 0A

Message Edited by xcator on 03-18-2006 01:17 PM

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@VCraig wrote:
For my own satisfaction and before I shell out ~$500 for the latest and greatest video card I want to hear it direct from the card manufacturer that what ever their recommended 12v bus amperage is, that it IS the total of both rails.

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Craig

How many PS out there supply that much avg power on the 12v bus?

xcator

For my own satisfaction and before I shell out ~$500 for the latest and greatest video card I want to hear it direct from the card manufacturer that what ever their recommended 12v bus amperage is, that it IS the total of both rails.

Not sure I understand the question "avg power". The critical need to know requirement is the 12v bus amperage rating and if the amperage rating is per rail or the total of both rails.

Message Edited by VCraig on 03-18-2006 04:04 PM

you may never get that specific answer from a card mfg, but you can look at it from a different angle.  nvidia certifies specific power supplies for sli systems, here is one that is nvidia certified (among many)...check the specs on this Thermaltake and you will see the rating for both 12V rails as 18A max. each rail.

http://www.thermaltake.com/2005/purepower/w005758twv500/w005758twv500.htm

I believe this would indicate that the requirement is a combined output on the 12V rail, not an individual rail.

Actual power to individual components do become an issue with the ultra high end systems.  nvidia specifies what an ultra high end sli system (dual 7900gtx or dual 7800gtx 512 w/fx-60 or 955EE) needs in terms of power, here's what they say: "You must have a power supply that can provide a minimum of +12V @ 22A of dedicated power for the two graphics cards. Of this 22A requirement, +12V @ 5.5A must be available to each of the two PCI Express 6-pin auxiliary power supply connectors. The remaining 11A must be supplied to the motherboard for dedicated graphics card use."  nvidia also separately certifies power supplies for the ultra high end system configs.

for high end sli sysems (dual 7800gtx 256) "Minimum of 500-600W Power Supply with a minimum of +12V @ 30A for all PC components."

mid-range sli systems (dual 7800gt) "Minimum of 450-500W Power Supply with a minimum of +12V @ 26A for all PC components."

I know the gen3 is not sli, but this gives an idea of power requirements.  I know you want proof and I hope you can get it.  Of course nvidia lists retail power supplies only and not oem's such as Dell.  It's uncharted territory for the older machines for sure. 

 

 

 

Thanks for the info folks. I actually picked up the Gen 3 because of vcraigs recommendation about a year and a half ago. Thanks by the way, I am still extremely happy with it. I was toying with idea of ordering a new machine in a couple of months and couldn't decide to do that or replace my aging x800 xt.  By the way, I remember reading an article a while back (Hard OCP?) that did a test with games using cpu only and the result was that there was no noticable difference in score using a machine that is a p4 3.0 and above. That is to say my p4 3.6 will not bottleneck a 7900 GTX. What I am really curious about is how much performance increase will there be. Thanks again.