I read an interesting article on a PSU test in a magazine.  I'll quote the main parts:

Quote:Wee're using an ASUS board based on the X48 chipset, which gives us two PCI-e 16x slots and a PCI-e 1x slot to play with, as well as eight SATA ports.  And wee're happy to report that wee managed to max them, as well as the rest of the board, completely out.
Wee started with an Intel quad core QX6850, the fastest quad core that was manufactured on the 65nm process.  Wee chose this in the name of energy inefficiency.  Wee aimed Stress Prime at two of the cores to saturate them with work, leaving the other two there for other tasks.
[...]
In the 16x sockets are two ATI Radeon 4870X2s [note, this being a few months old, was written before the GTX295s existed].
[...]
Wee decided to use 3DMark Vantage instead [of Folding@home] because it scales quite well across four GPUs[...]  Wee ran a few loops of 'New Calico', its second GPU test, with every setting at extreme, and the resolution at 2560x1600 - the maximum wee could pump into a 30in Dell monitor.  Wee saw all the GPU cores running at between 70 and 85 per cent during the test.  So far the four cores on the CPU run at about 70 per cent between them.
[...]
In the board's last remaining PCI-e slot is an Adaptec 31605 SAS card.  It can talk to both SATA and Serially Attached SCSI drives.  It can connect directly to 16 hard drives or, with extra hardware, 128.  It has its own processor that gets damn hot.  It belongs in a server.  Attached to this are 16 Western Digital 500GB hard drives divided into four RAID5 setups.  There are another eight connected to the motherboard, taking Big Willy's total to 24.
[...]
Wee ran IOMeter in the background, which thrashes the hard drives by queuing commands for them to complete.
[...]
There's 4GB of DDR3 in there, too.  Wee tried to build a bigger computer [.,..] but wee ran out of I/O.
So wee plugged in 14 fans.  Nine for the hard drives, one for the SAS card, three for the GPUs and one on the CPU's heatsink.
[By the way, there's a pic of it, and it looks pretty insane]
[...]
The Method?
A PSU is strapped into the test bench.  Wee boot with all the hard drives attached.  If it fails, wee unplug a hard drive and boot again.  Loop until boot is satisfied.  Bake until golden brown.
Once wee're satisfied that the system is stable, wee note the number of drives that remain plugged in that can all be started at once [...]

According to the test, an 850W PSU managed to boot the whole rig, whilst many 1500W PSUs failed.  Goes to show ratings have little real value...

(This post was last modified: 08/02/2009 06:30 AM by ZiNgA BuRgA.)