WPCREDIT tweaks for the A64

[ahfung]

Max async latency of 5ns is very good.

If you want a 30 sec superpi score, you'll need approx 2766 MHz (11x251) from a S754 1Mb chip. Thats a tough ask on air.

Max async has quite some impact on performance, but there are two cases it has to relax:

1. Running more than 1 stick
2. Running at async

In my case my Hynix DT D43 can set max async to 7ns at 265MHz 2.5-3-3 for best performance. However once running 2 sticks, 8ns is a must for stability, and Vdimm won't help at all.

And at any non 1:1 ratio, 7ns is no go.

With only 1 stick, setting to 8ns won't let me go any higher.
Setting Max async to Auto in Lanparty BIOS is equal to 7ns in my case, for both 1 or 2 sticks.

Refresh rate (Tref) will have a healthy boost when set to 166 MHz 1.95us, but it might not apply to all memory.

My $0.04