
Chapter 1: Datasheet 1–13
Recommended Speed Grades
August 2014 Altera Corporation IP Compiler for PCI Express
Stratix IV GX Gen1
×1 62.5 all speed grades
×4 125 all speed grades
Notes to Table 1–9:
(1) The RX Buffer and Retry Buffer ECC options are only available in the hard IP implementation.
(2) This is a power-saving mode of operation.
(3) Final results pending characterization by Altera for speed grades -2, -3, and -4. Refer to the .fit.rpt file generated
by the Quartus II software.
(4) Closing timing for the –3 speed grades in the provided endpoint example design requires seed sweeping.
(5) You must turn on the following Physical Synthesis settings in the Quartus II Fitter Settings to achieve timing
closure for these speed grades and variations: Perform physical synthesis for combinational logic, Perform
register duplication, and Perform register retiming. In addition, you can use the Quartus II Design Space
Explorer or Quartus II seed sweeping methodology. Refer to the Netlist Optimizations and Physical Synthesis
chapter in volume 2 of the Quartus II Handbook for more information about how to set these options.
(6) Altera recommends disabling the OpenCore Plus feature for the ×8 soft IP implementation because including this
feature makes it more difficult to close timing.
Table 1–9. Recommended Device Family Speed Grades (Part 2 of 2)
Device Family Link Width
Internal Clock
Frequency (MHz)
Recommended
Speed Grades
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