A small granular-like precipitate may be detected microscopically on the cells after transfection using cationic lipid. This is normal. The presence or absence of this precipitate is not indicative of the transfection efficiency.
The precipitate can be caused by presence of excess EDTA or cationic lipid. Use DNA in water or, if in TE, use EDTA concentrations of <0.3 mM in the diluted DNA. Ensure concentrations of cationic lipid reagents do not exceed recommended amounts in complex formation.