how much power does a DVD burner require?

I have been upgrading a shuttle mini-PC to use a DVD RW drive and found that the drive would start up and read just fine but was unable to burn DVDs
The only difference that I have found between the drive (sony DW-Q30A) and my older LG combo drive (worked perfectly) is that the sony requires 1.5A vs the 1.3A for the combo. I think that I have maxed out the power supply by adding an Nvidea 6600 AGP card as an external DVD burner worked fine.

My question to everyone here is where can I get a low power DVD burner for my shuttle SN41G2 system or can I get an upgraded power supply?
Am i on the right track or have i missed anything obvious (the bios settings are fine and the jumpers on the ATAPI line are correct)

I tried both those web sites and according to them I should be fine, but the DVD burners still won't work.

I have noticed that DVD burners seem to require about 1.5-1.6 A (all are 12V) whereas the combo drive I was using required 1.3A so those sites both need a little updating if they are suggesting that the combo drive requires more power or they do not have figures for double layer DVD RW drives which could require more. So no help from either site.