15 Year Old be quiet 850W PSU Dies After Wrong Modular Cables for RX 9070 XT [2026]

By Indie Kings | September 19, 2026

Updated September 19, 2026: A Redditor named Sarkoth killed a 15-year-old be quiet 850W PSU by plugging in modular PCIe cables from a different unit during an RX 9070 XT upgrade, per Wccftech. With one power press came a thunderous roar and breaker trip, a reminder never to mix modular cables between PSUs.

be quiet 850W modular power supply unit with PCIe cables after failure during RX 9070 XT upgrade

Image: The be quiet PSU class involved in the modular cable mix-up. Credit: be quiet via Wccftech.

What happened with the 15-year PSU

Per Wccftech on September 19, 2026, Omar Sohail relays a Reddit post on r/pcmasterrace by Sarkoth at comments 1wkie4d. The user ran a be quiet 850W P9 unit for 15 years with a GTX 1080 Ti, then retired that card for a Radeon RX 9070 XT needing three 8-pin cables.

Not wanting to disturb meticulous cable management, the user plugged in available modular PCIe cables that likely belonged to a different PSU, per Wccftech. One press of power gave a thunderous roar, a snap of light, then the internal breaker tripped and shut everything down.

Wccftech notes the Redditor has not updated whether other parts died. The 15-year streak for that unit ended at that press, per the same report.

Why wrong modular cables kill a PSU

Modular PSU cables look standard on the component end but are not standard on the PSU end. Per Wccftech, pinouts differ between vendors and even between models from the same vendor.

A wrong cable can feed 12V into a ground or 5V pin. The result is a short through the PSU or board the moment power flows. Breakers and protections can trip, but after 15 years of capacitor aging they may not save every rail.

The RX 9070 XT needing three 8-pin cables raised the stakes here. More mixed cables means more chances that one wrong pinout shorts the unit.

Setup per Wccftech	Detail	Risk
PSU	be quiet 850W P9, 15 years old	Aged caps, unknown protections state
Old GPU	GTX 1080 Ti	Ran fine for years on original cables
New GPU	RX 9070 XT, three 8-pin	Needed extra PCIe cables, user reused loose ones
Cables used	Likely from different PSU	Wrong PSU-side pinout, instant short

What may have survived and what to check

Wccftech says the extent of damage is unconfirmed and that it reached out for damage photos. Until the user posts them, treat every connected part as suspect.

Check order is PSU first with a tester or known-good unit, then board for scorch marks, then GPU, drives, and RAM one at a time. Do not reapply power through the same mixed cables.

The breaker tripping is a good sign but not proof other parts lived. A short can pass through PCIe or ATX rails before protection opens.

Do not reuse: Any mixed modular cable from the incident, label and remove them.
Test PSU alone: Paperclip or tester only, no components attached.
Inspect board and GPU: Look for burnt pins, melted housings, and discolored PCB.

How to avoid this on your upgrade

Always use cables that shipped with the PSU running in your system, per Wccftech. If you lost them, order the exact cable kit for your model and revision from the vendor.

When upgrading to a three 8-pin card like the 9070 XT, route fresh correct cables even if it ruins existing management. Aesthetics are cheaper than a board and GPU.

Label spare modular cables by model the day you unbox a PSU. A zip bag with the model written on it prevents a 15-year-later mix-up.

Rule	Action	Why
Never mix	Use only bundled cables for that exact PSU	PSU-side pinouts are not standardized
Verify revision	Match model plus revision when ordering spares	Same brand can differ by revision
Replace with GPU	Budget a new ATX 3.1 PSU with old units	15 years exceeds most warranty and cap life expectations

The 15-year lesson for old units

A quality PSU can last a decade, per Wccftech, and this be quiet 850W reached 15 years on a 1080 Ti. That longevity likely built false confidence for the 9070 XT swap.

Old units predate ATX 3.1 transient handling and 12V-2x6 sense designs that modern high-power GPUs expect. Even with correct cables, a 15-year unit deserves retirement before a flagship-class upgrade.

If your PSU is over 10 years old and you are adding a three 8-pin card, replace the PSU as part of the GPU budget. Keep the old unit for a low-power spare, not a gaming rig.

FAQ

What PSU died?
A be quiet 850W P9 after 15 years, per Wccftech relaying Sarkoth on Reddit.

What caused the failure?
Modular PCIe cables likely from a different PSU plugged into that unit for a three 8-pin RX 9070 XT, per Wccftech.

Are modular cables interchangeable?
No. Per Wccftech, PSU-side pinouts differ by vendor and model, so mixing can short 12V to ground.

Did other parts survive?
Unconfirmed as of the September 19 Wccftech piece. The user had not posted damage photos.

What should I do before a GPU upgrade?
Use only cables bundled with your exact PSU or the vendor kit for that model and revision, per Wccftech.

Should a 15-year PSU be replaced anyway?
Yes for a modern high-power GPU. Age plus new transient loads makes replacement the safe path.

Bottom Line

A 15-year be quiet 850W did not die of age alone. It died because mixed modular cables turned a routine 9070 XT upgrade into a short, per Wccftech. Keep cable sets tied to their PSU model and retire decade-old units before they meet a three 8-pin card.