Davey has made eight changes, two of which are positional, from the side that lost to France on Tuesday for Wales's final Pool match against the young Pumas in Riom on Saturday. Two of those changes are up front, where Craig Mitchell replaces the injured Phil Osbourne in the front row and Will Jones gets his first start of the tournament at lock.
Behind the scrum, Maesteg's James Dixon will win his first cap at outside half to allow the Dragons' Aled Thomas to move to full back. Bridgend wing Roger Davies starts on the left wing with Bath's Tom Cheeseman moving from wing to centre in place of Tom Riley, who has picked up a minor shoulder problem. Chris Clayton returns to the right wing and Martin Roberts replaces Nicky Griffiths at scrum half.
"We were disappointed with the scoreline against France considering the effort we put into the game. We want to keep things as fresh as we can because we have everything to play for on Saturday," said Davey.
"If we can win with a bonus point, we can still get into the semi-finals, whereas if we come away with nothing, we could be at the bottom of the pile. The aim of our changes is to put extra pace and mobility into our side and I feel Will Jones can do that at lock while also adding an extra dimension in the line-out.
"We know we will have to match Argentina's strength up front when they have the ball but we want to play them on our own terms when we are in possession or they will dictate the game. We have a number of new faces in our squad which means that almost every game we have a new team on the field but that is the nature of this tournament for us."
Backs Coach Dai Rees echoed Davey's thoughts on a need to move the ball around against a heavy Argentine side. With four tries required for the bonus point the Welsh plans will be to attack at all times.
"We have made a clear decision to inject some pace into our side and hopefully that will make for an exciting game. Aled Thomas adds pace and regional experience to our back three, Roger Davies is the quickest of our backs and Chris Clayton is an out an out wing who also has a good physical presence," said Rees.
"James Dixon is unpredictable and I'm hoping that will help to break the game up which is what we will have to do against Argentina, while Martin Roberts brings something different to the table compared to Nicky Griffiths but overall they will probably share the game time in this tournament. Again, we will hopefully make the most of Martin's passing game to break the game up tomorrow."
Wales Under 21: A Thomas (Dragons); C Clayton (Blues), T Cheeseman (Bath), D Hewitt (Blues, captain), R Davies (Bridgend); J Dixon (Ospreys), M Roberts (Ospreys); R Gill (Blues), E Shervington (Ospreys), C Mitchell (Ospreys), W Jones (Dragons), D Day (Scarlets), C Everett (Worcester Warriors), R Shellard (Blues), A Powell (Blues)
Replacements: D George (Scarlets), R Cornock (Dragons), J Connors (Glamorgan Wanderers), C Dicomidis (Blues), R McCusker (Scarlets), D Lockyer (Blues), N Griffiths (Ospreys)
(v Argentina, Saturday 18 June, Riom kick-off 4pm local time/3pm BST)