WP_Query + random

Is there any way to get this

<?php 
$pc = new WP_Query ('category_name=cat1&posts_per_page=5'); 
?>

but each time display a RANDOM different batch of 5 ones?

1

Please try this:

$args = array(
    'category_name'  => 'cat1',
    'posts_per_page' => 5,
    'orderby'        => 'rand',
);

$pc = new WP_Query( $args );

where 'rand' should give you a random order of your posts.

For more info check out the Codex on WP_Query order parameters here.