I remember a rather old thread here saying that Dell computers should not be expected to last very long under BOINC usage.

Does that also apply to their newer, gaming/high performance models such as the Alienware Aurora series? Those seem to be about the first I've found that provide sockets for more than one GPU board, without a PSU power rating much higher than needed to overheat my computer room.

If those are not a good choice, what other brands and models would you suggest for someone no longer able to build a home-brew computer, or even lift one, and interested in more than one GPU with a PSU rated no more than 450 Watts?

Cat's don't change their stripes - avoid!
The PSU 'rating' is just that, a 'rating'. It's not the amount of power it will use or heat it will generate. The PSU is key to a good system. Invest in a good PSU and your system will last longer, use less electric and generate less heat.

There are lots of sites that allow you to build on-line; select the components and the shop puts them together. I would say a local shop would build to spec for you.

Not sure why you want more than one GPU? Usually one high end GPU is the better option. You would really need to specify a price range. These days a good system (32nm) doesn't use a massive amount of power <100W, but if the PSU must be 450W that really leaves you in a position to only get one high end GPU or two mid range GPU's. 2 mid range GPU's would be less efficient than one high end GPU; would use more power, generate more heat, cause more cooling issues, reduce system longevity. Then you have the CC2.0 vs CC2.1 issue (performance). Even with a good 450W PSU I would not want to use more than about 350W.

Agreed with skgiven, don't put 2 GPUs with 450 W limit. Take a decistion NVIDA/AMD.
If you look at wikipedia you can optimize GFLOPS/ watt

Unfortunately, the PSU rating is the only item I have with much relation to the limit of how much heating my computer room can stand.

Sure, you can use a Dell. Don't be surprised if you hear a loud "SNAP!!" followed by a funny smell. Your lights will probably go out from the blown circuit breaker, but that's okay because the resulting fire will provide plenty of light.

Seriously, I wouldn't try to get too much out of a retail machine. Most of them seem to use the absolute bare minimum power supply, as well as other inexpensive components. That's how they get their prices so low and still manage to make some profit. You never, ever want to push the upper end of a power supply, even a high quality one. Using just one good high end video card will be reaching the limit of power draw for a 450W PSU when you take into account the CPU, chipset and all that. 2 GPUs on a 450W PSU is simply out of the question, unless you use low end cards that when combined are less powerful than one good higher end card.

If you really want to know about ATI video cards, they're very powerful but have poor support from the distributed computing world. They are fairly horrible in folding@home compared to Nvidia, and there are fewer BOINC projects that support them as well. Probably the only project I've seen where ATI actually pulls far ahead is MilkyWay@home. Bottom line, with your limited options you would probably be better off sticking with a nice Nvidia card for now.

Agreed with skgiven, don't put 2 GPUs with 450 W limit. Take a decistion NVIDA/AMD.
If you look at wikipedia you can optimize GFLOPS/ watt

Unfortunately, the PSU rating is the only item I have with much relation to the limit of how much heating my computer room can stand.

PSU rating is a good mesure, it's like having a stove in the room of that power, but remember, don't take it to the limit.
The only thing you can do in a situation like this is try some artificial ventilation as a fan or liquid refrigeration (too complicated unless you don't do that as a hobby do-it-yourself)

Even if you decided to go AMD, the best thing to do is wait for the competition to arrive, and prices to fall.

Probably the only project I've seen where ATI actually pulls far ahead is MilkyWay@home. Bottom line, with your limited options you would probably be better off sticking with a nice Nvidia card for now.

Each project seems to favor one brand of card or the other. The whole point is figure out where you want to crunch using a gpu and then go out and get one, not the other way around.

If you look at wikipedia you can optimize GFLOPS/ watt

I remember a rather old thread here saying that Dell computers should not be expected to last very long under BOINC usage.

I've seen too many Dell systems with board and PSU failures to ever even consider one for GPU crunching.

Does that also apply to their newer, gaming/high performance models such as the Alienware Aurora series? Those seem to be about the first I've found that provide sockets for more than one GPU board, without a PSU power rating much higher than needed to overheat my computer room.

Cat's don't change their stripes - avoid!
The PSU 'rating' is just that, a 'rating'. It's not the amount of power it will use or heat it will generate. The PSU is key to a good system. Invest in a good PSU and your system will last longer, use less electric and generate less heat.

If those are not a good choice, what other brands and models would you suggest for someone no longer able to build a home-brew computer, or even lift one, and interested in more than one GPU with a PSU rated no more than 450 Watts?

There are lots of sites that allow you to build on-line; select the components and the shop puts them together. I would say a local shop would build to spec for you.

Not sure why you want more than one GPU? Usually one high end GPU is the better option. You would really need to specify a price range. These days a good system (32nm) doesn't use a massive amount of power <100W, but if the PSU must be 450W that really leaves you in a position to only get one high end GPU or two mid range GPU's. 2 mid range GPU's would be less efficient than one high end GPU; would use more power, generate more heat, cause more cooling issues, reduce system longevity. Then you have the CC2.0 vs CC2.1 issue (performance). Even with a good 450W PSU I would not want to use more than about 350W.

Two GTX470's (or 560 Ti 448) would require too much power, so better with one higher end GPU (GTX570 or GTX580). Here a GTX460's does ~half the work of a GTX470, so there is really no point to get two, well not for crunching.

Ironic, my Dell Studio XPS led me accidentally to GPUGRID (01-19-2011), when Seti went down and no WU were available to crunch. So, in a way, a Dell can be sort of a good thing too. LOL

BTW, it’s paltry Dell Alienware 1792mb GTX 260-192 core, is still giving me a daily RAC of 85,000+, with a total credit of 28,263,758 (03-27-2012). Currently running at 68% fan speed, with a temperature reading of 62C. Capable of running a I4R48-NATHAN_FAX4, in less than 24 hours. Not to bad for a non recommended card and it’s downtrodden host, but YMMV

I am not using a Dell computer but I sometimes buy less expensive components to keep machines running. Yesterday, my GTX 580 ate my LSP Ultra 750W power supply. It was a great site to see and it smelled really bad. The LSP Ultra lasted for a couple of years but one about 30 days with my GTX 580. Overclocking that card is torture for a power supply.

Today, everything is up and running again on an OCZ 700W PSU. Who knows how long this one will last? It has 4 +12V power rails. I would assume the 6 pin PCI-E and the 6+2 pin PCI-E connectors are on different rails.

Good PSUs are expensive and most system builders use the minimum possible device. Guess my next PSU is going to cost a few more bucks but for now, we are running.

I kinda like torture testing my computers...

Good PSUs are expensive and most system builders use the minimum possible device.

I have several Dell's crunching. One XPS480 (no longer for sell) is running for 3 years now running 24/7 without problems and without extra cooling. Its a quad with running 3 cores for BOINC.

Other systems are Dell's as well and crunch normally at night and weekend as they have 800 to 1100Watt power supplies. All run without problems. I have only one not Dell and that one is causing a lot of problems.

So yes use a Dell.

A good PSU should feel like a giant lead brick. If instead it has the approximate weight of a cotton ball, you are almost guaranteed to have issues with it.