Replacement PSU

[Kolmagorov]

In November 2014 I built (with some help from the forums here) this machine:

PCPartPicker part list / Price breakdown by merchant

CPU: Intel Core i5-4690K 3.5GHz Quad-Core Processor (Purchased For $210.00)
CPU Cooler: Cooler Master Hyper 212 EVO 82.9 CFM Sleeve Bearing CPU Cooler (Purchased For $25.00)
Motherboard: ASRock Z97 PRO4 ATX LGA1150 Motherboard (Purchased For $100.00)
Memory: G.Skill Ares Series 8GB (2 x 4GB) DDR3-1866 Memory (Purchased For $79.00)
Storage: Crucial MX100 256GB 2.5" Solid State Drive (Purchased For $110.00)
Storage: Western Digital Caviar Blue 1TB 3.5" 7200RPM Internal Hard Drive (Purchased For $58.00)
Video Card: MSI GeForce GTX 760 2GB TWIN FROZR Video Card (Purchased For $220.00)
Case: Fractal Design Define R4 (Black Pearl) ATX Mid Tower Case (Purchased For $80.00)
Power Supply: XFX 550W 80+ Bronze Certified ATX Power Supply (Purchased For $35.00)
Monitor: Dell P2414H 60Hz 23.8" Monitor (Purchased For $220.00)
Total: $1137.00
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2016-01-06 11:30 EST-0500

About three weeks ago, it started sometimes shutting down (complete shutdown, not even a blue screen of death) when I would start a game. I tried switching graphics drivers, swapping out RAM, updating the BIOS, reinstalling windows, and nothing helped. I even tested the PSU with a multimeter and all the voltage reported back perfect. Over time the system became more and more unstable until it would rarely make it to the desktop. However, when I switched in a PSU from an older build, all crashes stopped and it's been perfectly stable for 24 hours. So I pretty much have to blame the PSU.

I currently have an open ticket with their tech support, but I may just take this as an opportunity to upgrade to a fully modular and/or more powerful PSU.

So my questions are: If I were to upgrade from a GTX 760 to a 970 or similar, would I need to up the wattage? Also, what model would you recommend for a reliable fully modular PSU?

[mrgreenthump]

You could continue with XFX as they are mostly seasonic rebrands nowdays. Though definately get a seasonic rebrand if you go XFX again.

If you want to stay at ~500W, I would probably go for this XFX or this EVGA. Both are high tier PSUs really and seasonic rebrands(EVGA is better quality parts though). There are cheaper fully modulars though, but PSU is one of the most important pieces in your system, so to skimp on it ain't always a good idea.

As to wattage question 500W is fine for most builds nowdays, so 550W should cover any current GPU with 4690k nicely.

[moremana]

No, even with a 970 you would be pressed to run over 430W depending on case fans and how many usb devices you have connected.

As mrgreen stated 500-550 would be more than adequate unless you went sli, even then your max load would be 490-520W