That PSU is bare minimum for the NVidia 220 card and it may be that
the rest of the hardware is pushing it a tad too much. That would
explain the intermittent nature of this problem.

According to NVidia the 220 needs a 400W PSU but with a 12V rail which
can push out 25A - that Thermaltake PSU has twin rails of 14A and 15A
which doesn't leave much over for the rest of the system ???

Get back to the builder with this and see what they say - I'd have
gone for a 600W PSU in this rig myself !! Apart from anything else
that 430W one is going to be run close to maximum and that's not good
for efficiency or longevity !!

The builder may argue otherwise of course but if they'll agree to a
switch for a 600W PSU for just the difference in cost then I'd go for
it