GpuZ 12v sensor graph showing drops, is this normal?

[kr0sys]

Does the graph on the sensor tab for the 12v and vddc normally show drops down to way low? the 'show min setting' on 12v shows 1.38v, the vdcc shoes 0.00, and the vddc current also show 0.00 for the min values. There is also an angular drop off in the graph sometimes. The problem is that the screen will freeze for a moment, go black, then recover with vista telling me that the display driver stopped responding. This was also happening while boinc (dist computer project manager) was running full load with gpu use enabled. Since turning off boinc, the problem has remained.

System specs: everything is at stock frequency
-asus 6850
-780g motherboard
-phenom 2 955
-450w roswell psu (12v1 reads 14amp, and 12v2 reads 16amp)
-2gb ddr2 800 <-apparently this isnt a bottleneck

I know that the psu is really cutting it close. Do those amp readings on the psu's 12v rails seem low? I wanted to forgo a new psu with the recent upgrade of the cpu and vidcard because I can't afford it, rotf, but I think I'm gona have to splurge and with the idea that I'll eventually get a 800 series chipset motherboard for the pciE 16x/16x and mate this 6850 with another, I'll have to get something at least 650wattsh. Check out these screens of gpuz.. The extra wide dips are when the power loss occurs, which is once per pic. Is this normal? TIA

 

[kr0sys]

Decided to fire up boinc again and use the gpu, the graphs were solid for the first couple of minutes, but then this happened. So far the display hasn't frozen though.