I`ve solved the problem.
This is the article from Intels site:
Abstract: This document describes why 430VX does not support x4 SDRAM configuration.
Problem: There have been questions regarding 430VX chipsets working with 4M x4 SDRAMs.
Solution: The SDRAMs, due to their synchronous nature, put extra pressure on meeting timing specifications. Specifically at 66MHz (15ns clock period), the clock skew and Hclk signal integrity become major issues. Consequently, it is purely a loading/timing reason why we cannot support x4 SDRAMs. We do support x8 or x16 SDRAMs because now loading is halved.
Future chipsets are heading for higher speeds and will be even harder to meet the timings. In summary, 430VX can drive 8 loads per row. This sets our lower limit at x8.
I changed my memory (which had only 4 chips) for SDRAM with 16 chips and it works well.
Thanks for your time...