Radeon HD 4890 (RV790) is still 55nm based and is basically a higher clocked version of RV770. The RV790 card comes with 10 layers PCB and is 9.5" long with a new dual slot cooler. We told you previously, there are 2 versions; standard and OC edition. The OC edition will come later in April. The price for standard 512MB edition is US$199 while the price for 1GB OC edition is US$299.
Radeon HD 4750 and 4770 is 40nm based and we already have seen a preview of it. Price of HD 4750 is expected to be around US$99 while HD 4770 is priced at around US$119. Apparently, the yield is so good that AMD decided to pull in from May to early April release to give GeForce GTS 240 and 9600 GT a run for its money.
For an exclusive preview of RV740, read our preview.