Your local township or just leave them outside for the recycle people. They are suppose to collect IT e-waste according to the usual DA spam I get in my inbox.
If all of that fails you can take a ride to Coastal Park off Baden Powell drive.
Its the biggest dump i have ever seen!
Only thing is the place stinks to high hell and they don't accept asbestos
Milnerton municipal dump next to Killarney race track The Cape Town entrance is open to residents not business (therefore don't use your logo vehicle) where most rubbish can be dumped excluding building rubble and kitchen waste. They are big on recycling and take any computer parts or whole. Only one trip a day and they are open 7 days a week. Very helpful and friendly they are.