Henry, unless you’ve found one that you can name — the bank named in this thread, HSBC, isn’t one — there is no bank in Singapore that will charge $0 on both the inbound and outbound on foreign currency, even if you already have that foreign currency. You’ll pay some sort of fee for the transfer in, out, or both. Moreover, banks can (and do) change their fees at any time. Not only is there no deposit insurance, there is no assurance the outbound fee won’t change (rise) even if the inbound is free.
You must prudently take these factors into consideration, into your calculation, if you’re a rational person. Exactly how you calculate these factors is up to you, but “zero is the wrong answer.”
If HSBC has a branch in Malaysia, and the ringgit fixed deposit will be in Malaysia, different story.
On edit: HSBC Singapore charges S$10 for a telegraphic transfer in and a minimum of S$15 for TT out (HSBC Premier status, but could easily be more even with Premier status). It’s right in their fee schedule. If you’re trying to deal in ringgit cash (please don’t) then the fees are much higher. So, deduct these fees from your fixed deposit yield calculation, plus adjust as you see fit for zero deposit insurance and fee increase risk. Also include TT fees, if/as applicable, to/from your Malaysian bank.