The power supply (PSU) is the part people most often try to save money on, and the one that can take the rest of the PC down with it when it fails. In Lebanon, where power arrives through a mix of state supply, generators, inverters and batteries, a good PSU matters even more. Here's how to size one properly and what to look for beyond the wattage number.
Step 1: Estimate your PC's power draw
Almost all the power in a gaming PC goes to two parts: the graphics card and the processor. Add up:
- Graphics card: its rated board power. Roughly 115–180W for 1080p cards, 220–300W for 1440p cards, 360–575W for the top 4K cards.
- Processor: its TDP or rated power. Around 65W for most non-K/non-X chips, 120–170W for high-end Ryzen, 125W base (and much higher boost) for Intel K chips.
- Everything else: motherboard, RAM, SSDs, fans and USB devices add about 50–100W.
Then add about 30% headroom and round up to the next 50W. The headroom covers short power spikes from modern graphics cards, keeps the PSU in its efficient range, and leaves room for a future upgrade.
Typical PSU sizes by build
| Build type | Example parts | Recommended PSU |
|---|---|---|
| Office / integrated graphics | Ryzen 5 8600G, no graphics card | 450–550W from a reputable brand |
| 1080p gaming | Ryzen 5 / Core i5 + RTX 5060 or RX 9060 XT class | 550–650W |
| 1440p gaming | Ryzen 7 / Core i7 + RTX 5070 or RX 9070 class | 650–750W |
| High-end 1440p / 4K | Ryzen 7 X3D + RTX 5070 Ti / RX 9070 XT | 750–850W |
| Top-end 4K | Ryzen 9 / Core i9 + RTX 5080 / 5090 | 850W (RTX 5080) to 1000W+ (RTX 5090, which NVIDIA rates at a 1000W minimum) |
When in doubt, follow the graphics card maker's recommended PSU wattage from its product page. It already includes headroom for a typical system.
Step 2: Wattage is only half the story
A cheap "700W" unit can deliver less clean power than a quality 550W one. Look for these:
80 Plus efficiency rating
| Rating | What it means in practice |
|---|---|
| 80 Plus / White | Basic efficiency. Fine for low-power office PCs. |
| Bronze | Good value for budget and mid-range gaming builds. |
| Gold | Less heat and noise, usually better components. The sweet spot for gaming PCs. |
| Platinum / Titanium | Highest efficiency. Worth it for PCs that run long hours under load. |
Higher efficiency matters a little more in Lebanon than elsewhere. Every watt wasted as heat is a watt your generator subscription, inverter or battery has to supply.
Protections
A good PSU shuts itself down safely instead of damaging your parts. Look for OVP (over-voltage), UVP (under-voltage), OCP (over-current), OPP (over-power), SCP (short-circuit) and OTP (over-temperature). Reputable brands list them on the box and spec sheet.
ATX 3.x and the 12V-2x6 connector
Many recent NVIDIA cards use a single 16-pin power connector (12V-2x6, the successor to 12VHPWR). An ATX 3.0/3.1 PSU with a native 16-pin cable is the cleanest option, and these PSUs are also designed to handle the short power spikes of modern GPUs. Whatever you use, push the connector in fully and avoid bending the cable sharply right at the plug.
Modular cables
Fully modular PSUs let you plug in only the cables you need, which means less clutter and better airflow. Semi-modular is a good middle ground. Non-modular is fine for budget builds if the case has space to hide cables.
Why PSU quality matters more in Lebanon
- Switchovers between state power and the generator cause cuts lasting a few seconds, and sometimes voltage spikes when the supply returns.
- Voltage swings on generator and grid lines can stress cheap units with weak protections.
- Heat: a PSU working in a hot room during summer runs closer to its limits. Gold-rated units waste less power as heat.
A quality PSU handles these far better, but it isn't a substitute for a proper UPS. Our guide to protecting your PC from power cuts explains which UPS works with modern PSUs.
PSUs to avoid
- No-name units where the wattage is the only spec listed, with no efficiency rating and no protections.
- Cases sold "with a 450W PSU included" at a very low price. That PSU is rarely suitable for a gaming GPU.
- Small power adapters listed as "power supply", which are for routers and phones, not PCs.
- Very old units reused from a previous PC. Capacitors age, and older PSUs may lack the GPU connectors you need.
Frequently asked questions
Is a bigger PSU a waste of money?
Slightly oversizing is sensible because of headroom and upgrades. Buying double what you need adds cost without benefit. The 30% rule is a good balance.
Does a higher-wattage PSU use more electricity?
No. The PC draws what it needs. A 1000W PSU running a 400W system doesn't pull 1000W. Efficiency (Bronze vs Gold) affects how much extra is lost as heat.
Can I use my old PSU in a new build?
Only if it's from a reputable brand, less than about 5–7 years old, has enough wattage, and has the right connectors for your GPU and CPU. When in doubt, replace it, because a failing PSU can damage new parts.
What size PSU do I need for an RTX 5070?
For a typical gaming build with an RTX 5070 and a mid-range CPU, a quality 650–750W unit is the usual recommendation. Add your exact parts in the builder to see the estimate for your build.