Ruby you wouldn't be able to walk to the HSBC at Nabq from the Coral Sea Imperial (if that is the hotel that used to be the Conrad ?), you would need to get a cab, so depending on how much you are changing up and the exchange rate that Garry gave at the hotel, the cab may cancel out any savings, if that is all you are going to Nabq to do.
If you were going up there for a mooch round anyway, then it might be worth hanging on and changing the money there as there are quite a few banks. I used one of the Arab ones, it was modern and with brill air c o n ditioning, which you are grateful for when you have walked from your hotel like we did.