My ATX power supply stopped working. After opening it up and probing around (caps discharged), I discovered the 10A/250V fuse (white tube with leads) had blown. I have a ton of the common glass tube fuses, but the 10A ones I have will be a difficult to fit. They're all 6x30 instead of the 5x20 size of the blown one. The rest of the fuses are 240V/5A or lower.
The closest value I have at that size is 12A/250V, but it seems a bit sketchy at a 20% higher rating. In general what's the safety margin for switched mode power supplies?