What is DDR2 Clock Frequency Setting (Affect Niche Stack and VIC functionality)...?

Dear Friend's

I am using Altera ESDK-Cyclone-III board

My Application is to collect data from Synchronous port (1 Mbps) and forward it to Ethernet Port (TCP packets) & for testing i am using RS232 Port. but both ports and Vectored Interrupt Controller (VIC) won't work at time

1. Setting ddr2_bot clock from 165 to 150 mhz Results

1.1 Quartus: Critical Warning: Timing not met

1.2 Ping Stop Responding

1.3 VIC receive all the interrupt

2. Setting ddr2_bot clock from 150 to 125 mhz Results

2.1. Quartus: Critical warning removed: Timing not met

2.2. Ping Stop Responding

2.3. VIC Collect all the Interrupt

3. Setting ddr2_bot clock back to 165 mh Results

3.1 Quartus: Critical Warning: Timing not met

3.2 Ping Responding

3.3 VIC not able to receive all the interrupt

3.4 after interrupt activity ping also stop responding

Regards

Kaushal