A while back, I've bought a Dell XPS 420 and was very satisfied with it. However, seeing that the 8800 GT is a really good deal now, I have been wondering if the power supply that Dell has is sufficient to run it. Currently, it has a 375W power supply in it (that's about as much as I know so far) and it runs quite a few things already, such as the LCD on top for sideshow, a media card reader with a Bluetooth radio, an 8600GTS, and a modem (I have no idea why I didn't deselect that as an option). I've read on the internet that Dell has shipped these computers with a 375W PSU with an 8800GT when Nvidia states that 400W is the minimum for these cards. Some people feel its insufficient but others say that Dell rates their power supplies differently. To no avail, I did not find a clear answer so I'm asking you guys to help. Here are my PC specs if needed:

Dell XPS 420:
Intel X38 Chipset (BTX Motherboard)
Intel Q6600 @ 2.4GHz
Dell 3 GB Dual Channel DDR2 SDRAM @ 667 MHz
Nvidia 8600GTS
7200 RPM 320GB Hard Drive

I feel that this Dell is quite limited because it does have an X38 chipset which could run the more recent processors but does not allow things like overclocking (there is one person who was able to get an XPS 420 to outperform a 720, with the exception of graphics since the X38 doesn't support SLI ). If there is no way I can upgrade it's power supply, I might as well send it back and maybe buy the new XPS 630 (which hopefully, is more upgradeable because it's motherboard looks like an upside-down nForce 650i SLI ATX motherboard, although I could be mistaken).

I would have built my own computer, but I do need an operating system and I got this thing on a November when my dad's laptop died (he needed my old computer as a replacement but I needed it for school work :schwitz. Any suggestions?

From what I can see the 8800GT at peak draw requires around 40W more than the 8600GTS (110W vs. 71W). I've no idea how much headroom you have left on that PSU though. Take a punt if you feel lucky?

Edit: Hmm. Just seen another source claiming 138W for the 8800GT. That's pretty extreme...

Find out exactly what the peak draw is for the model you're interested in buying!

Hmm, well in a forum, one said that a 8800GT overclocked (g92, I'm assuming that's the new one) draws about 84W and in a test, a q6600 draws about 104W max. However, I'm still worried since I do have an LCD for Sideshow that I can't really disable (or I get the BSOD. Boo.), and an Optiarc DVD-RW drive that I have no knowledge about. According to a PSU calculator on Newegg, this PC would need at least 558W of power with an 8600GTS (wtf?), but this PC is using a 375W PSU and runs games very well. So confusing...

Those power calculators are always rubbish (dunno why) - apparently my system is 200W short of booting too. Never knew!

Why buy a whole new system anyway; can you not just swap the power supply out?

I have no idea since Dell has a BTX case and supposedly uses weird connectors. Also, good BTX power supplies are hard to come by, or I might not be looking hard enough. And also, a very small amount of people have switched their power supply and they didn't tell what kind of PSU they used. It's probably because this computer was released so recently that few people did anything to it (otherwise it would void their warranty). I think the computer was first released by the end of summer, plus or minus a month or two, so I doubt that anyone but the people who don't care about the computer did anything to it.

The reason that I might want a different system (Dell XPS 630) is that you are able to overclock it with ESA, supports both Crossfire and SLI, has a nice power supply, comes with an 8800GT, and is ATX. The base model is about the same price as the XPS 420 that comes with 3GB RAM and and an 8800GT but would obviously perform better and is upgradeable on the long run. The only situation where I don't see it performing better is on CPU performance if someone put a QX9650 in the 420 and overclocked it with RMClock.

http://extreme.outervision.com/psucalculator.jsp

Maybe this help's you

1) btx power supplies are just atx 2.0s afaik
2) anand produces the most reliable numbers i have seen so far: http://www.anandtech.com/showdoc.aspx?i=3175&p=7 keep in mind that those are for the whole pc and not just the cards measured at the plug so you have to take ~70-85% psu efficiency into account which brings the numbers down a little

Those numbers seem very reliable. Now I'm not so worried about how much power is left since that test rig has more and faster RAM and a faster CPU. Thanks a bunch for the help!
Now all that's left is a recomendation of a good PSU for the Dell if all else seems to fail.