be quiet! Straight Power 11 Platinum 750W Quiet Performance Power Supply | Fully Modular | BN642
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AI Verdict
A dead-silent 750W Platinum power supply with premium internals, held back slightly by stiff cables and a stingy 5-year warranty.
The 750W capacity and 93.7% Platinum efficiency easily handle modern gaming rigs while staying under 21 decibels. The stiff cables make it a nightmare for compact cases, restricting this to standard mid-towers.
If you are building in a Mini-ITX case, look for an SFX power supply with flat ribbon cables or individually sleeved paracord cables.
Regret Score™
Medium RiskLower is better — measures purchase-regret risk from real buyer complaints, review credibility, and product maturity
Issues discovered after purchase
Critically weak dimension
Amazon rating vs actual quality
Chance this product isn't for you
Pros
- Hits 93.7% efficiency at 50% load, reducing heat output
- 135mm Silent Wings 3 fan maxes out at just 20.8 dB(A)
- Internal wire-free DC design improves airflow and component longevity
- Four independent 12V rails provide stable power for high-draw GPUs
- Uses 105°C-rated Japanese capacitors for long-term reliability
Cons
- 5-year warranty falls short of the 10-year standard from competitors
- Double-sleeved round cables are extremely stiff and hard to bend
- Lacks a zero-RPM fan mode for idle operation
Dimension Scores
Delivers up to 93.7% efficiency with four dedicated 12V rails for stable GPU power.
The 135mm Silent Wings 3 fan peaks at an incredibly quiet 20.8 dB(A) under full load.
Wire-free internal design and 105°C Japanese capacitors are excellent, but the 5-year warranty deducts points.
Fully modular design helps, but the rigid, bulky sleeved cables are frustrating to route.
Best For
- Noise-obsessed builders running high-end air cooling setups
- Mid-tower ATX builds with plenty of cable routing space
- Systems with power-hungry GPUs like the RTX 3080 or 4070 Ti
Not Recommended For
- Small form factor (Mini-ITX) builds where stiff cables won't fit
- Buyers demanding a decade-long warranty for peace of mind
Watch Out For
- The PSU emits a loud mechanical 'click' when turning on and off. This is just the inrush current relay doing its job, but it sounds exactly like a short circuit.
- The included cables are thick, round, and double-sleeved. You need at least an inch of clearance behind your motherboard tray to route the 24-pin ATX cable comfortably.
- You only get a 5-year warranty. If you expect a premium Platinum unit to guarantee 10 years of coverage, you will be disappointed.
Full Specifications
| ASIN | B085ZBT81N |
| Brand | be quiet! |
| Color | Black |
| Series | straight power 11 |
| Wattage | 750 watts |
| Model Name | straight power 11 |
| Form Factor | ATX |
| Item Weight | 3.74 pounds |
| Manufacturer | be quiet! |
| Connector Type | PCI Express |
| Cooling Method | Air |
| Output Wattage | 750 Watts |
| Item model number | BN642 |
| Compatible Devices | Personal Computer |
| Product Dimensions | 13 x 9.75 x 4 inches |
| Item Dimensions LxWxH | 13 x 9.75 x 4 inches |
| Item dimensions L x W x H | 13 x 9.75 x 4 inches |
What Buyers Say
The acoustic performance dominates user discussions, with buyers consistently praising the near-silent 20.8 dB(A) operation under heavy gaming loads. The internal wire-free design keeps temperatures low, but the external cables are a major pain point. Builders constantly complain about wrestling the stiff, double-sleeved cables behind motherboard trays. The loud mechanical click during startup and shutdown causes widespread panic until owners learn it is just a harmless relay switch.
“It's so quiet I had to use a flashlight to check if the fan was spinning, but wrestling those stiff cables into my case was a workout and the startup click still scares me.”
Common Praise
- Fan noise is completely undetectable over standard case fans
- Handles RTX 3080 and 4070 Ti power spikes without shutting down
- Funnel-shaped intake design keeps dust buildup to a minimum
- Modular ports on the unit are clearly labeled and easy to access
Common Complaints
- Startup relay click sounds like a blown fuse
- 24-pin motherboard cable is too stiff to bend 90 degrees easily
- 5-year warranty feels inadequate for the premium price tag
- Included cables take up too much space in the PSU shroud basement
Ownership Tips
- The startup click never goes away, you just stop jumping out of your chair after a week.
- You will likely need custom CableMod extensions if your case has less than an inch of rear cable clearance.
- The fan never stops spinning, but it pushes enough air at idle to lower ambient case temperatures slightly.
Frequently Asked Questions
Why does it make a loud click when I turn my PC on or off?
That click is the physical relay switch for the inrush current limiter. It protects your components from power surges and is completely normal.
Are the cables flat or braided?
They are thick, round, double-sleeved cables. They look premium but are notoriously stiff and difficult to bend in tight spaces.
Does the fan turn off completely when the PC is idle?
No, the 135mm fan spins constantly. It runs at such a low RPM that it stays around 20 dB(A), making it virtually inaudible anyway.
Is 750W enough for an RTX 4070 Ti?
Yes. The 750W capacity and four independent 12V rails easily handle the transient power spikes of modern GPUs without tripping protections.
How long is the warranty?
You get a 5-year manufacturer warranty. This is shorter than the 10-year warranties offered on similar Platinum units from competitors.
Buying Guide
You are paying a premium for silence. The 135mm fan and internal wire-free layout make this one of the quietest 750W units on the market. You must have a spacious case to accommodate the rigid, thick cables. Do not buy this expecting a decade of warranty coverage, as it caps out at 5 years.
80 PLUS Platinum
Converts up to 93.7% of wall power into PC power. Less wasted power means less heat, which allows the fan to spin slower and quieter.
Four 12V Rails
Splits the power delivery into four separate lanes instead of one massive highway, adding an extra layer of overcurrent protection for high-draw graphics cards.
Fully Modular
You only plug in the exact cables your components need. You leave the rest in the box, freeing up space for better airflow.
Alternatives
If you need easier cable routing or a 10-year warranty, search for an 80 PLUS Gold or Platinum unit featuring flat ribbon cables and a single 12V rail.
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