Psu power consumption tst

Hello,

I have this pc:
- Asus m4a785 tdv evo
- Athlon x4 635
- HD5770 vapor-x
- 1 x Hard drive seagate 1500 GB
- 1 x 2 GB ddr3 markvision 1333Mhz
- 3 x 80mm 12V fan
- Thermaltake tr2 600W

I had tested the power consumption of my pc, and I tested my pc with gta4, cod5.

I tested the current in the 120V ac line, whit a small tester.




I got confusing results, When my pc is iddle, the tester shows ~ 0.8 A
When Im playing cod5 whit all max, the tester shows ~ 1.1 A
When Im doing a benchmark whit gta4, the tester shows ~ 1.2 A

power consumption = V * I = 120 V rms * 1.2 A rms = 144 W max.

why? I mean, what am I doing wrong? is it true the psu is only getting 144 W? I dont think so, but I hope you can tell me .

thanks for reading.


edit:

-ammeter : multimeter UNI-T UT33A

- I messured the current like this:

in this draw, the lamp is the pc, and the battery is the 120V line. and the tester was messuring AC current.