Yet another 240W power supply question...

My brother has a HP dc5800 small form factor desktop pc with integrated graphics (240W proprietary power supply; Intel Core 2 Duo E8300 2.83GHz; Intel Q33 Express Chipset; 4GB RAM (4-1GB dimms); 500GB SATA HD; Win7 Pro SP1 64-bit).

One year from now I will build him a $500 gaming pc, but in the meantime he just wants to upgrade the graphics card without adding anything else to his desktop. He will be a casual gamer with this pc until he gets the new gaming pc.

I used a kill-a-watt and measured the total watts of his pc. During boot it fluctuates between 45-60W; Idle is 42W; And running a couple different video stress tests it maxes out at 72W.

Based on my simple calculation, I get 240W * .8 (80% efficient) = 192W - max 72W = 120W available.
Adding a video card and disabling the on board video should free up more watts.

I think what throws me for a loop is this statement from HP's website:
"PCIe x16 slot: 1 low-profile Max power per slot: 25W".
I'm thinking this means a new video card would take max 25W from the slot, and additional power from the power supply.

Ultimately I want to put in the low profile SAPPHIRE 100326LP Radeon HD 6670 1GB 128-bit GDDR5 PCI Express 2.1 x16 card from Newegg ( )

Here's my questions (and I do apologize in advance for the long post)
(1) Can anyone please help me with the rails / volts / amps on this power supply? See power supply info below

(2) Is the Radeon HD 6670 pushing it for this system (Max TDP 63W)? On Newegg's website there's 8 comments on this card and half of them are people with small power supplies (Dell Optiplex 760 SFF with 235W PS; Dell Inspiron 530S with 250W PS; and Dell Optiplex 380 with 235W PS)

(3) If the Radeon HD 6670 is out, what other card would you recommend? I've seen the Radeon HD 6450 mentioned (31W Max TDP)

I took a look at the power supply label and here's the specs:
HP Spare Number: 460889-001 : Power supply (240 Watts) - With six DC output connections, 80% efficiency rating - With power factor correction (PFC)

This is all that's listed on the power supply. There's no other info about max wattage on rails.
100-240V ~ 5A : 50-60Hz : 240W MAX
+5.08V=17A +3.33V=15A +12V=7.5A
+12Vcpu=11.5A -12V=0.15A +5.08Vaux=3A

Thanks in advance,
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  1. I would wait for a low profile card (with the special bracket) for $10 after rebate. Frys and newegg sometimes have these; they might work with your weak power supply.
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