Something else, as I've used the same PC power supply for maybe 5 or 6 years now, with no problems.
A poor connection can cause so much resistance that you can burn out a power supply. The charger is pulling say the 7 to 8 amps it needs to run, but because of a poor connection the power supply may have to be putting out it's max to get enough to the charger to run.

Things like alligator clips are for temporary use, and dependent on the quality, are sometimes only rated for 1 amp. You should look at a more permanent type connector. I run a Deans connector on mine for input/ output, and have the opposite style on my 3 chargers.

In the field I use a male/female accessory style plug. The female portion is hard wired to the battery, the male end connects with another Deans to the charger. And the adapters are rated for 20 amps.

Using the Dean's, I've rigged up probably a dozen different adapter harnesses, for both the chargers to charge different type packs, and different type power sources to power them.