Cooling options at actual scale — rough 2D layout study

Back to the electronic-load project

Start with B, your preferred 50 mm cooler, and C, the 40 mm chipset cooler. Their body sizes are much closer to this 5 W load than desktop CPU coolers. D borrows the laptop blower architecture with documented commercial parts. These are layout studies, not a new PCB design or thermal qualification.

Open full-size drawing · Dimension data

What the dimensions mean

Every panel uses the same drawing scale. The existing PCB is 72 × 104 mm. Except I, the study retains that board outline and puts the cooler beside it to leave the board top available for probing. This requires relocating Q1 to the cooler interface and reworking its short electrical connections; these are not drop-in placements on Board34. Green rectangles are board outlines, not an assertion that the existing components have been rearranged. The teal 18 mm strip is a proposed probe-access reservation, not the current test-point coordinates or the full probe-head swept volume. Gold circles reserve the concept of four corner machine pins, not their drilling coordinates.

The orange planning boxes add 5 mm between board and cooler, plus 5 mm on every outside edge for a first carrier/fastener allowance:

width = PCB width + cooler width + 15 mm

length = max(PCB length, cooler length) + 10 mm

Those clearances are design assumptions, not verified tool or airflow clearance. Wires, connectors, exhaust clearance, frame strength and probe-head travel can enlarge them. R10's 151 × 120 × 69 mm is the actual previously modeled assembly envelope; new boxes are not equally mature evidence. Heights below are cooler body heights, not complete molecule heights. Do not add these dimensions to a fabrication drawing.

Size and mounting comparison

B's illustrative plan area is about 14% below R10, C about 20% below, and D about 17% below under the stated carrier allowances. I would be about 34% smaller, but depends on an entirely unproven PCB shrink. These are bounding-box comparisons, not scaffold slot counts. Thin laptop hardware can still occupy a large area.

Your preferred 50 × 50 × 12 mm option

Exact listing. Seller image labels a 50 mm side, 12 mm thickness and 41 mm mounting-foot pitch. The title also mentions 26 mm bore spacing; that is insufficient to define a PCB hole pattern. Confirm which holes the two dimensions refer to, mounting-ear extents and spring-pin protrusion. The image shows a two-wire fan and specifications say two-pin. We must find a fitting tach-output fan; changing it can change the 12 mm height. It is not yet a qualified cooling module.

Observed browser price on 13 October: $19.13 promotional/new-shopper versus $23.45 crossed out. Your supplied URL carries a different $22.05 offer. Budget roughly $19–24 for the listed assembly before tax, then add the feedback fan, electrical isolation, clamp and carrier. These are listing snapshots, not purchase quotes. Seller AI-generated overview was excluded from technical evidence.

Two arrangements deserve comparison:

• Beside the PCB (B): 137 × 114 mm illustrative carrier; cooler leaves board top uncovered. Q1 needs an edge mounting arrangement with short connections and adequate strain relief. This is the lower-risk starting geometry for probe access.
• On a dedicated PCB cooling bay: an exploratory 80 × 104 mm PCB could reserve a 50 mm cooler bay, 5 mm separation and a 20 mm probe lane across its width, leaving 5 mm total edge allowance. With the same outer carrier margin, this is a 90 × 114 mm target envelope. It is wider than today's PCB but potentially much smaller as a complete molecule. The cooler covers part of the PCB, so every needed test point must be moved out from beneath it; other components need a real placement exercise. This is a packing hypothesis, not a fit proof.

Q1 contact insulation, clamping and package height add to the listed cooler height. The supplier's GPU/northbridge spring pins were designed for a different contact stack; neither their force nor their height is automatically suitable for TO-220. Do not machine into an unidentified cooler base or heat pipe.

Compact commercial alternatives

C: 40 mm chipset assembly. Seller listing gives a 40 × 38 × 35 mm sink and 45/55 mm total heights with 4010/4020 fans. Adjustable bracket span is advertised as 43–82 mm, not a universal square bolt pattern. Observed bare sink $5.19, 4010 assembly $8.67, 4020 assembly $9.14. The 3-pin listing still needs a verified tach pinout. This has the smallest ready-assembled body in the shortlist, at greater height than B; no verified thermal curve yet.

D: documented blower architecture. Delta BFB04512HHA-CZ0T drawing, PDF page 7 specifies a 45 × 45 × 10.3 mm body, three mounting holes on a 38.5 mm coordinate spacing and 150 mm leads. This is a 12 V part: our existing 5 V auxiliary supply cannot power it directly. Control/feedback circuitry and the complete suffix-specific electrical interface require review. It is a blower, not a complete heatsink. The ATS 25 × 25 × 30 mm sink has mounting ears outside the fin body and 30 mm mounting pitches. Coupling its taller fin field to a 10.3 mm blower outlet needs a transition duct; the sketched 10 mm transition is only a space reservation. Pricing for this pair remains unquoted.

E/F: standardized CPU ecosystems. The AXP90-X36 manufacturer page provides a dimensional drawing, four 6 mm heat pipes, copper base and 92 mm PWM fan. NH-L9i manufacturer infosheet gives 95 × 95 × 37 mm. These offer replacement ecosystems and documented mounting, but side mounting consumes more plan area than the present molecule. They merit a later higher-power variant, not an assumed higher power rating for this board. Current prices not verified for these exact revisions.

G: tower reference. Silver Soul 110 manufacturer specifications provide a documented 94 × 94 × 110 mm comparison. A tower saves space only relative to a larger footprint cooler; its height and mechanical leverage matter in a scaffold. Your AliExpress tower has selectable 2/4/6-pipe and fan variants, and its actual selected-variant dimensions remain unresolved. The default $11.19 2-pipe/one-3-pin-fan selection must not inherit dimensions or capability from a six-pipe image. Adding a second fan adds depth and does not imply twice the heat capacity.

Laptop modules: promising architecture, no universal mounting standard found

Your ThinkPad X1 module places a blower/fin bank away from its cold plate. Its $48.99 listing offers a thin architecture, but no trustworthy dimensioned drawing was found. The 185 × 86 × 13 mm lead mentioned earlier is not a manufacturer specification and is not sufficient for CAD or ordering for fit. Panel H is deliberately labeled illustrative: we cannot conclude its actual molecule envelope from that lead. Rotation/overlap might reduce the box, but only if the cold plate lands on Q1 and all probe paths remain clear.

Your ThinkPad W530 dual-contact module, labeled FRU 04W3626/04W3627, likewise has unresolved overall dimensions, plate offsets and mounting heights. No invented outline is included. Its extra contact plate is unnecessary for the present D1 design and could obstruct probing. We should not choose it merely to cool both devices.

Laptop modules are model-specific mechanical assemblies. Catalog blowers such as D are a more documented way to borrow the architecture, though they still require a compatible heatsink and duct. A smaller blower by itself is not evidence of a smaller complete cooling solution.

Mounting standards are not interchangeable

Intel LGA115x/1200 use 75 × 75 mm and LGA1700 uses 78 × 78 mm mounting-hole pitch. Both exceed our current 72 mm board width. AM4's pattern is 54 × 90 mm; fitting its hole rectangle does not establish component, pin or backplate clearance. A separate carrier can take the cooler load instead of enlarging the electrical PCB solely for socket mounting.

Fan frame dimensions and heatsink mounting patterns are separate. For example, Noctua's 40 × 40 × 10 mm NF-A4x10 PWM uses 32 × 32 mm mounting pitch. It is not automatically a drop-in replacement for the preferred cooler's inset fan. No universal GPU/chipset or laptop cold-plate mounting interface was established by this research.

Thermal and probing checks before choosing

D1 remains PCB-cooled: the saved Board34 screen uses ~0.513 W, eight thermal vias and predicts 30.2°C still-air rise, below the 35°C board-rise limit. Shrinking its copper area invalidates that carryover assumption. Q1 is the primary cooler load; no second cold plate is required by this study.

Keep 5.5 W Q1 screening, 40°C ambient and existing temperature gates. The prior lumped sink budget is at most ~1.63 K/W before added margin. The new spatial screening suggests an extra spreading penalty at the old offset Q1 contact, so the historical R10 lumped pass is not qualification of any new arrangement. CPU TDP labels, seller wattage claims and fan RPM do not establish installed thermal performance.

Next design choice: develop B beside the existing board and B on the dedicated 80 mm board bay far enough to compare real probe access, alongside C's cheaper/taller option. Preserve USB-C edge access, four large machine pins, D1 copper, short Q1 electrical paths, independent fan supply, tach fault protection, intake/exhaust paths and access to all test points. No full 3D mockups, PCB edits, orders or power-rating changes were made for this comparison.

Research and diagram date: 13 October 2026. Supplier dimensions are nominal. Image B is the supplier's annotated product image, retained as dimension provenance; all layout drawings are original conceptual 2D work.