System in IDLE = 155W
System Wattage with GPU in FULL Stress = 188W
Difference (GPU load) = 33W
Add average IDLE wattage ~10W
Subjective obtained GPU power consumption = ~ 43 Watts
If the PSU is of GOOD quality it will be fine, 300 is enough. However if it is of poor quality it won't be. I've known HP (a while ago) to put some sub-par PSUs in their system. If we knew the exact model of the PSU it would be beneficial.
If only you can delete stupid posts by stupid people :
Intel Core i3 at 3.1 Ghz
8 GB Ram
1 TB HD
Okay first of all the i3-2100 consumes 40wat idle to - 90/100 watt stressed
8 GB Ram = 10 Watts
1Tb Hdd = 30/40 WAtt , if sata powered
CD DVD Combo another 30/40 Watt
7750 = maximum capacirty for PCI power fed is 75 Watt so lots do some math people will ya:
100 + 10 + 40 + 40 + 75 = 265Watt maximum stressted out computer , add couple of fans and some usb devices thats an extra 20 Watt =
285 Watts , and this is if running prime and burning a cd/dvd at the same time and running a Game at full setting as well as copying files to an external usb drive
^ This is hilarious.
You'll be fine - that is a very low power system. The HD 7750 is a very efficient card, and draws all power from the PCIe slot. Even if the PSU is low-quality and can't supply the full 300w it claims, you've still got a ton of headroom. If your motherboard has a PCIe x16 slot, then HP is obviously confident that the PSU can power it.