A definite...MAYBE? The SSR-550FX is a great quality (Tier 1) 80+ Gold PSU with 3% Load Regulation, all the protections you may need, and a 10-year warranty. You could potentially be running it at 80% of it's capacity for extended periods during gaming time, so as long as you're not in a room with an ambient temperature of 40°C, (and your PC case has adequate ventilation) you'll be OK. It is an 80+ Gold (90% efficient @50% capacity) PSU, so expect some heat and noise (the PSU's ''120mm Hybrid Silent Fan'' will be running near max RPM, and may be noisy). The PSU itself has 5x CPU/PCI-E (8-pin) modular cable connections, one of which will be used for your motherboard 4+4 or 8-pin connection. UNFORTUNATELY, Seasonic only supplies the SSR-550FX with ONE(1) PCI-E MODULAR CABLE -with- TWO(2) 6/8-PIN CONNECTIONS!! The Sapphire Nitro RX 5700 XT that you are purchasing requires TWO(2) 8-PIN PCI-E FEEDS from your PSU, and IT IS ABSOLUTELY NOT RECOMMENDED that you use the dual-head PCI-E cable for both connections ON ANY GPU/VIDEO CARD (consult your Seasonic Manual)!! So, physically? YES! Electrically? NO!! In conclusion, unless you can locate another Seasonic PCI-E cable for your SSR-550FX PSU - Dual PCI-E Head Seasonic NG40 (it doesn't appear that SeaSonic has a single-head PCI-E cable for the FX series), or just match the same ID# as the modular cable you already have. Otherwise, just make sure the PSU you replace it with has TWO(2) INDEPENDENT 8-PIN PCI-E MODULAR CABLES FOR THIS GPU!! (Four(4) if you plan on two(2) GPUs in the future!) Usually 650W-and-up Modular PSUs will have two(2) independent PCI-E cables, but check the box and on-line! Your target (for efficiency and durability of your PSU should be 30%-65% MAX CAPACITY for gaming load, so I would suggest a Gold-or-better 750W.) Good Luck!