Cyber Monday SFX power supply deals: SFF buyer watchlist

Cyber Monday SFX power supply deals have not reached the November 30, 2026 shopping event yet. This is a US pre-event price watchlist, not a roundup of confirmed Cyber Monday offers. On October 28, the CORSAIR SF750, SF850, and SF1000 were marked in stock on CORSAIR’s US store, while Best Buy displayed add-to-cart listings for the Thermaltake Toughpower SFX Platinum 850W and LIAN LI SP850P. The prices below are retailer observations, not verified checkout totals or proof of a Cyber Monday discount. If your small-form-factor PC needs a PSU now, confirm the exact model and shipping availability at checkout. Otherwise, record today’s baseline and compare it with the exact same listing on November 30. [1–6]

Quick verdict: which SFX PSU deserves your alert?

Best all-around performance-oriented candidate: CORSAIR SF850 (2024), CP-9020256-NA. The 850W model combines compact SFX size, an included modern GPU power cable, 80 PLUS Platinum efficiency and a 7-year manufacturer warranty. Hardware Busters’ independent SF850 review speaks favorably of its measured platform performance, but that review is not an in-house Geek Gaming Tricks test. CORSAIR showed $199.99 and an In Stock label on its US product page. [3, 9]

Best lower-wattage premium baseline: CORSAIR SF750 (2024), CP-9020284-NA. Choose it for a build whose actual CPU/GPU power needs and manufacturer recommendations fit 750W with adequate headroom. Its compact SFX enclosure and Type-5 modular cabling match the rest of the modern CORSAIR SF family. The US listing showed $174.99 and In Stock. A 750W rating should not be treated as automatically sufficient for every high-end GPU. [2, 10]

Best value-oriented 850W alternative to verify: Thermaltake Toughpower SFX Platinum 850W, PS-STP-0850FNFAPU-1. Best Buy displayed $139.99 with Add to cart and Thermaltake as the marketplace seller. Thermaltake’s own US storefront showed $219.99 but also conflicting “Sale Sold out” and “Add to cart” text. Those are two distinct storefront observations, not a verified price-match opportunity. Note its 103.8mm depth rather than assuming every SFX-labelled PSU is exactly 100mm deep. [5, 7]

Best long-warranty 850W alternative: LIAN LI SP Platinum 850W, SP0850P.B. LIAN LI specifies a standard 125 × 63.5 × 100mm SFX enclosure, 80 PLUS Platinum certification, ATX 3.1, a native 12V-2×6 cable and a 10-year warranty. The Best Buy page listed $181.49, sold and shipped by Newegg Official, with Add to cart; it is a marketplace listing rather than a Best Buy direct-stock guarantee. [6, 8]

Best true SFX 1000W option to monitor: CORSAIR SF1000 (2024), CP-9020257-NA. This is a real SFX model, not the longer SF1000L SFX-L product. CORSAIR’s US page showed $239.99 and In Stock. Its 1000W capacity is useful when the GPU maker’s recommendation and the full build’s power budget justify it; buying more watts cannot fix incorrect connectors or inadequate case clearance. [4, 10]

US price and stock snapshot — October 28, 2026

All amounts below are pre-sale reference prices, not confirmed Cyber Monday deals. “In stock” represents a US seller page label or visible Add to cart when accessed on October 28. Shipping destination, cart quantity, checkout taxes, seller membership and marketplace inventory may change the final result. The Best Buy listings were not independently completed through checkout.

Source markers [1–12] resolve in the accompanying evidence log.

Do not treat a retailer’s struck-through price or comparable-value label as independently verified historic pricing. The currently displayed $25–$40 price reductions on some pages are October offers or comparisons only. None proves a deal exists on November 30. Recheck the same seller and the identical SKU on Cyber Monday; if either changes, record the difference rather than making a misleading percentage claim. [2–6]

Shortlist breakdown: who should buy, wait, or skip?

CORSAIR SF750: compact premium pick for balanced systems

For a Mini-ITX gaming build with moderate total system demand, the SF750 offers a straightforward premium option. It has a 92mm fluid-dynamic-bearing fan with Zero RPM mode, 80 PLUS Platinum efficiency and ATX 3.1 compliance. CORSAIR identifies it as a true SFX PSU and lists a 7-year warranty. The Type-5 modular sockets are intentionally smaller than the older CORSAIR Type-4 ports, so a previous cable kit is not a safe reuse assumption. [2, 10, 12]

Buy or watch if: your exact CPU/GPU combination and the graphics-card maker’s PSU recommendation fit within a properly budgeted 750W system. Skip if: your GPU recommendation or upgrade plans require substantially more power, or your case and cable routing have not been measured. The manufacturer page’s $174.99 is a starting reference, not a Cyber Monday target guaranteed to recur.

CORSAIR SF850: a strong default for demanding Mini-ITX builds

The SF850 adds 100W of nameplate capacity over the SF750 while retaining the genuine SFX form factor. CORSAIR documents the 92mm fan, fully modular Type-5 cable set and ATX 3.1 compliance. The independent Hardware Busters review reports strong performance in its specific test context and notes Cybenetics Platinum efficiency and A- acoustic classification; readers should not generalize one review into a claim that every production sample is equally quiet. The seller listed $199.99, In Stock. [3, 9]

Buy or watch if: you want 850W headroom in a 100mm-deep SFX bay and value published independent electrical testing. Skip if: your rig does not need 850W and a cheaper correctly sized unit already meets its connector and safety requirements. Check the GPU’s own board-power/PSU documentation, not just a wattage calculator.

Thermaltake Toughpower SFX Platinum 850W: verify the total deal

Thermaltake lists this exact part as ATX 3.1-compatible, 80 PLUS Platinum, fully modular, with a 125 × 63.5 × 103.8mm chassis and a 90mm fan. The manufacturer specifies the 12V-2×6 (12+4-pin) cable as 450W on its US technical page. A GPU requiring a higher-rated native cable should not be assumed compatible simply because the connector physically fits. Verify the graphics-card instructions and connector/cable rating first. [7]

Best Buy’s $139.99 listing is attractive as an observed pre-event listing, but the marketplace seller is Thermaltake; the maker’s own shop showed a conflicting higher page price and mixed stock wording. Compare actual shipping, return window and seller identity before treating the lowest displayed number as a buy-now recommendation. Buy or watch if: this specific 450W-rated GPU cable fits your target GPU and the Best Buy checkout confirms the offer. Skip if: you cannot verify the seller’s stock or the GPU cable requirement. [5, 7]

LIAN LI SP850P: standard depth and a longer warranty

LIAN LI’s SP Platinum 850W is specified at the standard SFX depth of 100mm, with ATX 3.1, a flexible modular cable set, a 92mm FDB fan and a 10-year manufacturer warranty. The manufacturer’s SP Platinum documentation lists a native 12V-2×6 600W cable. That cable rating is not a promise that a given 850W whole-system build has unlimited GPU headroom; the PSU budget still includes CPU, motherboard and peripherals. [8]

The $181.49 Best Buy page has an Add to cart button and identifies Newegg Official as the seller. That arrangement can involve different return/shipping terms than items stocked and sold directly by Best Buy. Buy or watch if: you prioritize a true 100mm unit, warranty duration and the documented cable complement. Skip if: you require a retailer-direct purchase or need independent testing beyond the evidence reviewed here. [6, 8]

CORSAIR SF1000: 1000W without moving to SFX-L

The SF1000 combines 1000W capacity with the standard SFX envelope; it uses the same Type-5 modular connector family and a 92mm cooling fan. Its manufacturer US page listed $239.99 and In Stock. This is not interchangeable with a CORSAIR SF1000L listing, because SFX-L normally adds 30mm of PSU length. In a tightly packed case, that space can block a fan mount or make GPU cable bends difficult. [4, 10]

Buy or watch if: a supported high-end GPU and CPU demand a 1000W-class PSU and the case specifically requires SFX length. Skip if: your system is comfortably served by 750W or 850W, or the added capacity displaces money better spent on cooling or storage. Do not confuse wattage with efficiency certification, acoustic behavior or actual connector compatibility.

SFX vs. SFX-L: a deal is useless when it does not fit

A standard SFX chassis is approximately 125mm wide × 63.5mm high × 100mm long, while SFX-L retains width/height but stretches the length to about 130mm. CORSAIR documents that difference explicitly. The Thermaltake model in this list is slightly longer than nominal SFX depth (103.8mm), making actual clearance verification worthwhile even with an SFX-marked chassis. Check the case’s published PSU limit, power-cord orientation, fan grille and the space available for its modular plugs. [7, 10]

Also measure how long the included 24-pin motherboard, EPS CPU, and PCIe/GPU cables must travel. Short bundled SFX cables can be convenient in an ultra-small case but inadequate in a larger enclosure that merely supports an SFX bracket. Use the PSU maker’s supported replacement cable or extension strategy if needed; never substitute a cable from a different modular PSU just because both connector shells appear identical. [12]

Three checks before comparing any sale price

1. Fix the exact power requirement. Identify your CPU and exact graphics-card board model. Review the graphics-card maker’s recommended minimum PSU capacity and connector count, then account for your full build and a reasonable upgrade margin. A 750W, 850W or 1000W label is not a substitute for this check.

2. Verify mechanical and connector fit. Compare your case’s PSU bay against 100mm SFX, 103.8mm Thermaltake and 130mm SFX-L lengths. Confirm the included 24-pin/EPS cables and, for supported GPUs, the correct native 12V-2×6 power-cable rating. When installing a high-power GPU cable, follow its maker’s full-insertion and bend-clearance guidance. [7, 8, 10]

3. Record apples-to-apples seller baselines. Save the exact SKU, the specific US seller, displayed price, shipping/tax estimate, stock label and screenshot date. A refurbished CORSAIR SF850 listing or an older SF750 generation is not the same SKU as the new 2024 model. Do not use a different marketplace seller’s comparison figure as the current item’s MSRP. [2–6, 12]

How to check actual Cyber Monday offers on November 30

Cyber Monday 2026 is Monday, November 30 in the United States. Retailers can begin promotions earlier or extend them later; an event date alone does not verify any SKU’s promotional eligibility. [1]

1. Open the saved listing, not just search results. For CORSAIR SF750/SF850/SF1000, compare the manufacturer US product page with the saved October 28 reference. For Thermaltake and LIAN LI, open the same Best Buy listing and confirm which marketplace seller is fulfilling the order.

2. Check the actual transaction terms. Confirm the displayed final seller, stock, ZIP-code shipping cost, any coupon/membership requirement and the estimated total before paying. If a seller shows only a crossed-out reference price with no dated history, label that reference unverified.

3. Evaluate a target you set in advance. One practical method is to choose your own maximum out-the-door budget for the exact SKU today and flag it only if the November 30 checkout total is below both that budget and the October 28 comparable total. Example: if your personal ceiling for the SF850 is $190 before tax, $199.99 on the current manufacturer page does not yet meet it. The $190 figure is an illustrative personal ceiling, not an observed or promised promotion. [3]

4. Make the right call. Buy if the verified model is compatible, the actual seller has stock and the checkout total meets your target. Wait if the page offers no meaningful improvement. Skip a suspicious marketplace listing, a mismatched generation or a SKU without the correct GPU cable.

Common traps in SFX PSU “deals”

A high wattage number does not mean SFX. Some 1000W units are SFX-L; some 850W units sold in the same search results are full ATX. Verify actual dimensions, not just a product filter. [10]

“PCIe 5 ready” does not prove the included cable is right for your card. Check whether the exact SKU includes a native 12V-2×6 connector and its stated cable limit. Thermaltake identifies 450W for its model above; LIAN LI specifies a 600W cable for its SP Platinum line. Do not assume the same rating across brands. [7, 8]

Efficiency labels are not measured noise rankings. 80 PLUS Platinum concerns energy efficiency, not whether the fan will be inaudible beside your head. Independent tests such as Hardware Busters and Cybenetics provide a separate basis for considering noise and power quality, under their stated conditions. [9, 11]

Marketplace prices need seller-level verification. A product sold by a third party through Best Buy can have its own terms and delivery constraints. Treat “Add to cart” as a listing signal, not a guaranteed delivered purchase. [5, 6]

Modular cables are not universally interchangeable. CORSAIR warns that its Type-5 PSU cables do not interchange with Type-3/Type-4 modular cables; using an incompatible cable may damage hardware. The safe default is the exact PSU’s supplied set or accessories approved for that model. [12]

Frequently asked questions

Is an SFX PSU compatible with an ATX case?

Sometimes. Many ATX cases can use a suitable SFX-to-ATX adapter bracket, but a bracket is not guaranteed to be bundled with every PSU. Check the case mount, cable length, cable routing, and the specific product’s package contents before ordering. [8, 10]

Are SFX power supplies always noisier than ATX power supplies?

No blanket conclusion follows from size alone. SFX units usually have less room for a large fan, but fan control, power draw, internal design and operating temperature matter. Consult independent acoustic testing for the exact PSU and operating load instead of equating 92mm fan size with a fixed noise result. [9, 11]

Should I buy 1000W instead of 850W while it is on sale?

Only when your system’s documented need or credible upgrade plans justify it and the case and cable set still fit. If the full build is comfortably supported by a verified 850W model, buying 1000W does not automatically improve game performance. A good price on unneeded power capacity is not necessarily good value.

Can I reuse the modular cables from my old PSU?

Do not assume so. PSU-end pinouts vary across manufacturers and product lines. CORSAIR’s Type-5 family in this shortlist is not compatible with the older Type-3/Type-4 modular connectors. Check the official model-specific compatibility chart or use the supplied new cables. [12]

Are the listed October discounts Cyber Monday deals?

No. These are October 28 US page observations. Cyber Monday is November 30, 2026, and none of the cited retailer listings establishes a verified Cyber Monday offer. [1–6]

Final thoughts: set the alert before the event

For many performance-minded SFF gaming builds, the CORSAIR SF850 is the most straightforward evidence-backed starting point, while the SF750 suits lower-power builds and the SF1000 makes sense only when a higher power budget is warranted. The Thermaltake and LIAN LI 850W models provide distinct price, cable and warranty alternatives if their marketplace listings check out. Today, save the exact PSU SKU plus your case dimensions, GPU connector requirement and maximum checkout budget. On November 30, compare the same US seller’s verified checkout total against that record; buy only when the model fits and the price genuinely meets your target.