So is it a VRAM error or a RAM error which is the problem?
He shouldn't have to loosen timings unless his RAM is starting to go on him, which as mentioned, defeats the purpose of buying the lower latency RAM. You can try upping the DIMM voltage and see if that resolves any instability problems. Also run metest86+ just to be certain you don't have any bad sectors.
VRAM I don't really know what to say.
Intel C2D E6320 / AMD Athlon X2 3800+
Gigabyte 965P DS3 / DFI nF4 Ultra-D
2GB OCZ Gold PC2-6400 / 2GB OCZ Gold PC4000
eVGA 8800GTS 320MB / eVGA 6800GS 256MB
150GB Raptor / 74GB Raptor
2x500GB / 320GB
OCZ GameXStreme 850w / OCZ StealthXStream 600w