Ubuntu crashing randomly

[Spaztic One]

Sorry if this is the wrong place.

I'm having issues where my Ubuntu 15.04 PC is crashing at what seems like random. I have an AMD A10-7870k on a gigabyte F2A88XM-D3H with 8 GB ram and an antec Green 380 PSU. I literally have no idea why. Its a fresh build (received all the parts today) and it will sometimes show YouTube for 5 minutes or over 20 before crashing hard. Same for Slacker radio. Does anyone have any insight or direction to help me resolve the problems with this budget build media center PC?

 

[Outlander_04]

crashing hard ?

Like the power cord is pulled from the wall socket?

You should try a different power supply

 

[Spaztic One]

No, hard lockups. No mouse movement, no caps lock or num lock recognition. Only option is resetting the computer. Otherwise it works just fine.

Additionally, "sensors" reports

k10temp-pci-00c3
Adapter: PCI adapter
temp1: +0.0°C (high = +70.0°C)
(crit = +80.0°C, hyst = +79.0°C)

fam15h_power-pci-00c4
Adapter: PCI adapter
power1: N/A (crit = 95.05 W)

radeon-pci-0008
Adapter: PCI adapter
temp1: -2.0°C (crit = +120.0°C, hyst = +90.0°C)

The UEFI BIOS will report the CPU getting to 57c tops (let it sit in BIOS until the temperature stopped rising) so I don't think it's getting over temp.

 

[Spaztic One]

Ran memtest86 v4.2.0 for 14 hours, 5 passes and zero errors. I don't think that ruled the RAM out though as the UEFI BIOS reports the full 8192 MB DDR3, memtest reports 7111MB DDR2 (not DDR3) and Ubuntu reports 6.8 GB (unsure if the APU reserves RAM). Still getting hard freezes intermittently but it seems like it's only when watching internet videos (YouTube for example), though it is somewhat hard to narrow beyond that since that's the machines primary task and nothing in particular seems to cause the crash. It does seem like it's crashing less frequently, but maybe it was just in a better mood today lol