[SOLVED] Rx Vega 64, PSU not strong enough? Help

[Powershot]

Hello everyone. I just bought a Vega 64 2 days ago, after a bunch of reading i have undervolted it to:
p6 1452 freq 1000mv
p7 1552freq 1100mv
hbm 945mhz 980 mv

I have a Xeon 1650v2 now at 4.2( was 4.5 but lowered to see if i could get this stable)
ECC ram at 2400mhz
PSU ; AeroCool KCAS 650w gold
Resolution: 1080p , planing to get a 1440p later

So i've been trying to make 3d Mark Time spy but it's always rebooting after scene ends. The only time it actually made the test was when i puted CPU and RAM at stock settings and used same profile on card I said above. I have also tryed to run the card at stock settings and do the test, same story it reboots when scene is about to finish.
My PSU is a crap right ? Assuming its PSU i have looked already for Seasonic Focus + 850w 80 Plus Platinum ( 159€ ) and Evga Supernova 850 g3 Plus Gold( 140€ ). Between this two what would you advice?
Just wanna make sure PSU is the cause and hear a different opinion. Thanks

 

[Rogue Leader]

I agree its the PSU.

I have a Vega 64, not undervolted, but I had a Seasonic Prime Titanium 650w and in certain games it would crash the system due to its power draw. I upgraded to the Prime Titanium 750w and have not had any problems since. With your overclocked CPU and the Vega, I'm not surprised.

The Seasonic Focus Platinum 850w is a better PSU than the EVGA. I would highly recommend that one.

 

[WildCard999]

It sounds like the PSU is the issue, between the two the Seaonic Focus Plus is the better choice.

 

[Powershot]

Rogue and Wildcard999 really appreciate your help, i will be upgrading to the Seasonic one!
Sucks i can't make both of you best answer, sometimes you dont need trophy to be hero.Cheers and thanks once again.