If I understand correctly, let say you want to put RM10k into this FD 4.5% promo, you must put RM10k into OCBC savings account first. So effective rate is much lower because total fund is RM20k but only RM10k enjoy 4.5% and the FD is for 3 months only.

For few years? Go for Affin 4.38%. True interest rate.
OCBC 4.5% is a fake interest rate. Intentionally advertised the best rate to confuse ppl who are not savvy in banking deposit and don't understand the small prints.

One is apple (24 months) and the other is orange (3 months), after 3 months what will you get?

I just read the OCBC's terms and conditions, you have to put in 50/50 ratio for FD and CASA respectively.

For example, if you put RM 10K for FD to get 4.5%; then you need to put another RM 10K to CASA (select Smart Savers
to get max 3.05%).

So, 4.5% + 3.05% = 7.55% /2 = 3.775% max return for 3 months tenure.

Anyway, this promo has just ended.
Hopefully we can hear more exciting FD promo from OCBC next week...