You can identify the number of transceivers available in your Stratix® IV GX device by reviewing the ordering code which can be found on the top of the device.
Here is an example of a Stratix IV GX device ordering code:
The 10th character from the left indicates the transceiver count. For this example K is the character that denotes the transceiver resources available for your Stratix IV GX device.
The Characters available and associated transceiver count are listed below:
D = 8
F = 16
H = 24
K = 36
N = 48
For complete details on the Stratix IV GX ordering code format you can refer to the Stratix IV GX Device Handbook Volume 1 (PDF).