System Randomly Shuts Down After GPU upgrade

[pen-xv]

I updated from a GTX 550ti to a GTX 950. Ever since, the computer randomly freezes for a moment, then crashes. I have to hold the power button and restart. It does so more frequently when under a load (i.e. online gaming). However, it does so after awhile even when the pc is idle (say left running overnight). I updated to a new processor, and it is staying well under the max temperature (it was crashing with the old processor as well). I have the latest graphics driver. Nothing is overclocked. Any thoughts? I'm guessing that either the RAM doesn't like the new addition (the RAM has ran well otherwise for a long time), or that the GPU is bad. I know that this is a commong question, but any thoughts given my hardware specifics?

Specs:
Mobo: ASUS P5N-MX (latest BIOS), nforce 610i chipset.
CPU: CORE 2 E6750 upgraded to Xeon X5450
PSU: Roseill 700 Watt (don't remember the model)
RAM: 4GB DDR2 800 MHz
OS: Windows 10 Pro x64
HDD: WD 7200 RPM 500 GB 32MB

 

[maugusto]

you need a good PSU for the build, the current one only have about 28A per 12v rail
Depending on the model of GTX 950, you'll need a 6-pin or 6+2-pin PCIe power cable + a good PSU

 

[pen-xv]

you need a good PSU for the build, the current one only have about 28A per 12v rail
Depending on the model of GTX 950, you'll need a 6-pin or 6+2-pin PCIe power cable + a good PSU

Thanks for the answer. However, I did just verify the model as the RD700-M. Rosewill claims that this power supply will supply 56A for 12V. This should be more than enough to power the card, unless Rosewill's specs are off/misleading.