Sapphire Radeon HD 4890 1GB Review

Under the Heatsink

Once the heatsink is removed, we are able to see what looks like a standard HD 4870 1GB but as we will see below, there are a number of differences between the two cards. The back of the card doesn’t have anything of interest other than the fact that the HD 4890 heatsink mounting holes locations are identical to those on the HD 4870. This means that an aftermarket heatsink which fits on one will fit on the other. However, full-coverage water blocks WILL NOT fit as the VRM locations on this card are slightly different.


The RV790 core does not have any distinguishing marks on it other than the date to differentiate it from the core found on the HD 4870. However, it is slightly larger than the one used on the HD 4870.

On the other hand, the memory used on this particular card is Qimonda IDGV1G-05A1F1C-40X GDDR5 which operates at 4.0Gbps which is the same as the specification on the HD 4870. Before filing for bankruptcy Qimonda also released their “50x” ICs which operated at 5.0Gbps and some HD 4890 cards will be sporting Samsung 7.0Gbps chips so it will be interesting to see if any overclocked versions of the HD 4890 end up carrying the higher-spec’d GDDR5.


It is only when you place the HD 4870 and HD 4890 right next to each other that the differences become apparent. First of all, the HD 4890 uses a much more robust power distribution through the use of higher-end multi-phase inductors and VRM modules. The capacitors have also been seriously beefed up.


ATI also went ahead and slightly modified the heatsink design so instead of using a pair of larger heatpipes, it now uses a single large copper heatpipe and two smaller ones. This should spread the heat more evenly over the fin assembly and result in decreased temperatures. If you were wondering, we couldn’t find any major differences between the two aluminum fin assemblies.


Interestingly, the modifications didn’t just stop at the main heatsink assembly but also carried over onto the main contact base as well. As you can see, the HD 4890’s base (on the left) now incorporates a small heatpipe directly above the VRM contact area to dissipate heat faster. In addition, ridges have been added to increase the surface area for increased cooling potential.