Linear vs Switching

So i want to make a computer with an external power supply with an internal DC/DC power converter like the Pico PSU.

I've been looking for a high watt 12v external brick so i can use powerful graphics cards. My plan is to run a 12v line to the Pico PSU, and then separate 12v lines directly to the graphics cards' PCI-e power connectors.

In my search, the highest watt 12v brick i could find was 220w. I found a 330w brick, but its 19v which means i wouldn't be able to run it straight to the graphics cards' power connectors.

EDIT : thought i found a high watt linear PSU, read the specs wrong. Anyhow, question still remains below.

I looked up the differences between Linear and Switching PSU's, and this is what I came up with.

Linear Pro's:
Better load regulation
Better line regulation
Better ripple
Better transient recovery
Better EMI
Better leakage

Switching Pro's:
Better efficiency
Smaller Size
Lighter weight

Linear PSU's only get up to around 60% efficiency instead of 90% like in switching. And then linear PSU's have a lower power density (larger) and weigh more.

Are there any other issues with plugging a 12v line from a linear PSU directly into a graphics cards' power plugs?

Are there any other issues with linear PSU's? Are those 3 negatives the only reason PC's dont use linear PSU?

You're not going to find a high-wattage linear 12V power supply. Period. It would need an absolutely gigantic transformer.

Switching PSUs are probably inherently safer because when they fail they tend to shut down fast, but maybe not until they first do major damage to the stuff connected to them. OTOH a linear PSU often fails when one of its big output transistors shorts, causing the PSU to put out way higher than normal voltage, maybe forever until it's shut down. So it's more important for a linear PSU to have protective circuitry to shut it down if something goes wrong.

Linear PSUs tend to be less efficient and so need more heatsinking and better air flow. But probably the biggest contributor to the size and weight is the transformer because it works at 60 Hz line frequency rather than the roughly 60 KHz that switching PSUs typically use. For example, my 325 VA backup, which can probably put out almost 200W, has a transformer that's about a 3.25" cube, compared to maybe a <2" cube for a 1000W switcher.

I don't think linears offer any practical advantages, except for stuff that needs really low noise levels, like amplifiers that handle weak signals from phonograph needles or brains.

OTOH linears are a lot easier to design, especially if you need something that works off 120VAC; a lot, lot easier.