Motherboard is : GIGABYTE GA-M57SLI-S4 AM2 NVIDIA nForce 570 SLI MCP
Memory is : mushkin 2GB (2 x 1GB) 240-Pin DDR2 SDRAM DDR2 800 (PC2 6400)

Memory timings per website are 5-5-5-12 at 1.8v

Friends computer.

The MB auto set timing to 5-5-5, and the last value, precharge delay (tras) changes to 24 along with row cycle time (trc) at 24

With a manual settings at 5-5-5-12, CPUZ reports that he is at 5-5-5-18 and the trc also at 18. He tried lowering TRAS to 12 and TRC to 15, but cpuz showed it the same, 5-5-5-18

Also, Mushkin website says its supposed to be 1.8v He couldnt get stability (bsods) till almost 1.9v I found a few websites selling same memory and they list the voltage at 1.9v.

Any suggestions?

1.9 v is actually pretty good.

If the web site states 1.8v for 800 Mhz memory, I think there is a typo.

To my knowledge (someone correct me please)
DDR2 by spec is supposed to run at 1.8v
The only silicon available that runs at 1.8v is 667 Mhz (micron DG9 xx chips are a prime example)
Every memory manufacturer overclocks the memory to get the rated speed
to get 800Mhz 1.9 is good, some (like corsair specify 2.+)

Virtually all of DDR2 memory is the same 667 Mhz overclocked to a different level. The most that has been done is around 1250 / 1300 Mhz. Corsair XMS2 PC 10000 (1250 Mhz) is set to run at whopping 2.4 volts and comes with a cooler as internally it still runs 667 Mhz silicon.

The point is - I'm yet to see the chips that will clock 800 mhz at 1.8v.