Go with the Flow?

Chapter 10 — Case & Airflow

Your current Kolink Citadel Mesh is a capable mATX case — but the B760 ATX motherboard recommended in Chapter 3 won't fit inside it. This chapter explains why the case must change, recommends the Fractal Define 7 as the right replacement for this build, covers the airflow principles that keep an i7-13700K and RTX 3050 LP running cool and quiet, and walks through the optimal build sequence for putting everything together inside the chassis.

Verdict up front: Buy the Fractal Define 7. It accommodates the ATX motherboard, fits the NH-D15 G2 with 17mm to spare, includes a 5.25" optical bay the Kolink Citadel Mesh lacks, ships with three 140mm fans, and has outstanding cable management behind the motherboard tray. Budget ~£120–145.

Why the Kolink Citadel Mesh Has to Go

Replace
Kolink Citadel Mesh mATX
Max board sizemATX only
ATX board fits?No
5.25" optical bayNone
Max CPU cooler height~165mm
Included fans1–2 (budget fans)
Cable management space~15–20mm behind tray
Sound dampeningMesh — minimal
Keep for a future SFF build
Buy
Fractal Design Define 7
Max board sizeE-ATX (up to 285mm)
ATX board fits?Yes
5.25" optical bay2 × 5.25" external
Max CPU cooler height185mm (NH-D15 G2 = 167mm ✓)
Included fans3× 140mm Dynamic X2 GP-14
Cable management space~22mm + routing channels
Sound dampeningAcoustic foam on steel panels
~£120–145 on Amazon
mATX option if you don't want to change the case: If you choose the MSI MAG B760M MORTAR WIFI (mATX) instead of the ATX board, the Kolink Citadel Mesh can be kept. You lose one M.2 slot and a small number of PCIe lanes compared to the ATX version, but the core build is identical. The ATX board + Define 7 combination is recommended because the 5.25" bay, extra cooler clearance, and cable management space are worth the case upgrade for a machine you'll use for years.

Fractal Define 7 — Key Specifications

Supported Form Factors
ATX, mATX, mITX, E-ATX
The B760 ATX motherboard (305 × 244mm) fits perfectly. Future motherboard upgrades — even enthusiast E-ATX boards — also fit.
5.25" External Bays
2 × 5.25"
Rare in modern cases. Allows a Blu-ray drive or optical writer — a future upgrade option the Kolink Citadel Mesh doesn't support at all.
Max CPU Cooler Height
185mm
NH-D15 G2: 167mm (18mm clearance). Dark Rock Pro 5: 163mm (22mm). AK620: 160mm. All recommended air coolers fit with comfortable margin.
Included Fans
3× 140mm Dynamic X2 GP-14
Two front intakes, one rear exhaust — installed from the factory. These are quality fans with fluid dynamic bearings rated for 100,000 hours. No day-one fan purchase needed.
Fan Mounting Positions
Front 3×140 / Top 2×140 / Rear 1×140
Six 140mm fan positions total (or 3+3+1 if you mix 120mm). The build starts with positions 1, 2 (front) and 6 (rear) filled — three further positions for future expansion.
Max GPU Length
491mm (with front fan removed)
RTX 3050 LP is roughly 170mm long. Any GPU up to 491mm fits. RTX 4090 (336mm) would even fit — future-proof for any realistic GPU upgrade.
Drive Storage
2× 3.5" / 4× 2.5" (configurable)
Modular drive cage system. Configure as 2× 3.5" + 2× 2.5" or remove the cage for more GPU space. Your two SATA SSDs (870 EVO + WD Blue, both 2.5") mount in the dedicated 2.5" trays.
Sound Dampening
Acoustic foam on 3 steel panels
Top, left side, and front panels have acoustic foam lining. The Define series is consistently one of the quietest mid-towers at any price point — ideal for a workstation where fan noise matters.
Front I/O
2× USB-A 3.0 / 1× USB-C 3.2 Gen 2
USB-C Gen 2 (10 Gb/s) front port connects to the board's internal USB-C header — fast enough for an external SSD or NVMe enclosure. Two USB-A 3.0 ports for everyday use.
Dust Filtration
Front, top, bottom removable filters
All intake points have washable mesh filters. In a positive-pressure setup (more intake than exhaust), dust collects on the filters rather than inside the case — easy to maintain.
Dimensions (H × W × D)
543 × 240 × 475mm
A genuine mid-tower — deeper than average, which contributes to the generous cable management space behind the tray. Slightly larger than the Kolink Citadel Mesh but not dramatically so.
PSU Clearance
Up to 300mm (ATX)
TX550M is 150mm deep — half the available clearance. The PSU bay is behind a solid shroud that hides PSU cables and drives from the main chamber view.

Airflow Fundamentals

Case airflow has one goal: move cool air from outside the case past the heat-generating components and push hot air out. The i7-13700K and RTX 3050 LP are the primary heat sources. A well-designed airflow path prevents hot air from any component from re-entering another component's cooling zone.

AIRFLOW PATH — FRACTAL DEFINE 7 WITH THIS BUILD ┌───────────────────────────────┐ TOP │ (optional exhaust fans here) │ exhaust │ ↑ hot air exits via top │ optional └───────────────────────────────┘ ╔═══════════════════════════════╗ REAR ║ CPU cooler (NH-D15 G2) ║ FRONT 1× 140mm ←── hot air ←────║ fans push air L→R toward ───║ 2× 140mm exhaust ║ rear exhaust ║ intake ← (included) ╠═══════════════════════════════╣ (included) ║ Motherboard ║ ║ GPU (RTX 3050 LP) ║ ║ → GPU heat rises, expelled ║ ← cool air ║ by rear/top exhausts ║ from ╠═══════════════════════════════╣ outside ║ PSU bay (sealed) ║ ║ TX550M draws its own air ↓ ║ ║ from case floor vent ║ ╚═══════════════════════════════╝ Fan count: 2 intake (front) : 1 exhaust (rear) Pressure: Slight positive pressure → dust collects on filters, not inside Direction: Cool air in → past CPU/GPU → hot air out rear → optionally top
Positive vs negative pressure: When intake airflow exceeds exhaust airflow, the case is at slightly positive pressure. Air leaks outward through gaps rather than being drawn in — so dust enters only through the filtered intake points (front and bottom), not through every PCIe slot gap and panel seam. The Define 7's 2-in, 1-out stock fan config creates mild positive pressure. This is intentional — it keeps the acoustic foam panels sealed against the chassis and minimises dust ingress.
The PSU has its own airflow loop: The TX550M draws cool air directly from outside the case through the floor vent and exhausts it through its own rear grille. The PSU does not share airflow with the main chamber — it neither helps nor competes with the main cooling loop.

Fan Layout — Stock Configuration (Recommended)

The three included 140mm fans are all you need for this build's thermal load. The i7-13700K's heat is handled primarily by the NH-D15 G2's tower fans, not the case fans — case fans move air through the chassis, the cooler fans move air through the heatsink fins.

Intake
Front — Position 1 (bottom)
Size140mm
DirectionDrawing air in from front
StatusIncluded (Dynamic X2 GP-14)
Connects toMotherboard fan header (CHA_FAN1)
Intake
Front — Position 2 (top)
Size140mm
DirectionDrawing air in from front
StatusIncluded (Dynamic X2 GP-14)
Connects toMotherboard fan header (CHA_FAN2)
Exhaust
Rear — Position 3
Size140mm
DirectionPushing hot air out rear
StatusIncluded (Dynamic X2 GP-14)
Connects toMotherboard fan header (CHA_FAN3)
Optional Exhaust
Top — Position 4 & 5
Size2× 140mm slots
DirectionExhaust upward (hot air rises)
StatusEmpty — not needed for this build
Add if:You upgrade to a high-TDP GPU later
CPU Cooler Fans
CPU Cooler (NH-D15 G2)
Size2× 150mm (NH-D15 G2 included)
DirectionPush air front→rear through fins
StatusIncluded with cooler
Connects toCPU_FAN header (mandatory)
Fan header management: The B760 board has 4–5 chassis fan headers (CHA_FAN) plus the mandatory CPU_FAN header. Connect the three case fans to CHA_FAN headers and both CPU cooler fans to CPU_FAN and CPU_OPT (or use a Y-splitter from CPU_FAN). Enable PWM fan control in BIOS — the Define 7's fans and the NH-D15 G2's fans are all PWM-capable, so the board can ramp them down when temperatures are low and up during compile loads.

Optimal Build Order — The Right Sequence

PC builds go wrong most often not because of component mistakes, but because of sequence mistakes — installing something in an order that makes the next step harder or impossible. The order below minimises reaching into tight spaces and avoids having to partially disassemble what you've already built.

1
Prepare the case
Inside the empty case
Remove both side panels and the top panel (for access)
Install motherboard standoffs in the ATX pattern — nine brass standoffs in the correct holes. Check the Define 7 manual for the ATX standoff positions. Pre-installed standoffs in the wrong holes will short the motherboard.
Remove the I/O shield blanks where the motherboard's rear I/O panel will sit
Install the PSU (see Chapter 9) — do this while the case is empty for best access. Route the fixed 24-pin and EPS cables through their tray holes now.
Do NOT install the PSU after the motherboard — the cable routing becomes much harder with the board in place.
2
Prepare the motherboard outside the case
On a non-conductive surface (box lid, anti-static mat)
Install the I/O shield into the rear opening of the case (press firmly until it clicks into all four corners) — do this before the board goes in
Install CPU on motherboard (lever, triangle alignment, contact frame if using Thermalright)
Install RAM in A2+B2 slots
Install NVMe SSD in the primary M.2 slot (30° angle, retaining screw, heatsink)
Do NOT install the CPU cooler yet — it would make lowering the board into the case awkward
3
Install the motherboard into the case
Main chamber
Lower the motherboard into the case, rear I/O panel first — align it with the I/O shield cutouts
Align the board's mounting holes with the standoffs (all nine should line up simultaneously)
Hand-tighten all nine screws first, then torque them down in a cross pattern (centre first, then outer)
Do not fully tighten one screw before others are in — this can stress and crack the PCB. Cross-pattern tightening distributes pressure evenly.
4
Install the CPU cooler
Main chamber (board now in place)
Install the LGA1700 backplate through the rear of the motherboard (or use the Thermalright contact frame bracket if you bought one)
Apply thermal paste — pea-size dot at centre of CPU IHS
Mount the cooler standoffs/brackets, then lower the NH-D15 G2 in the correct orientation (fans aligned front→rear)
Tighten diagonal (X-pattern) to avoid uneven pressure
Attach both cooler fans and connect to CPU_FAN and CPU_OPT headers
5
Install the GPU
Main chamber
Remove expansion slot covers from the rear panel (1 cover for LP single-slot card)
Unlock the PCIe x16 slot retention clip
Insert RTX 3050 LP into the top PCIe x16 slot until the retention clip clicks
Secure the bracket screw to the case
Connect PCIe power cable if your LP variant requires it
6
Install the storage drives
Drive bays (PSU shroud area)
Mount Samsung 870 EVO in a 2.5" tray (no screwdriver needed for tool-free trays — slide and click)
Mount WD Blue SA510 in the second 2.5" tray
Connect SATA data cables from each drive to the motherboard's SATA ports (right-angle connectors point toward the drive, straight end to motherboard)
Connect the SATA power chain from the TX550M to both drives
Check the board manual — if an M.2 slot is shared with a SATA port (e.g. SATA5 disabled when M.2_2 is used), make sure your SATA cables avoid those conflicted ports.
7
Connect all motherboard cables
Main chamber
24-pin ATX — from behind tray, connect to board's main power header (firm push, latch clicks)
4+4 EPS — from behind tray top hole, connect to CPU power header top-left of board
Front panel connectors — power switch, reset switch, power LED, HDD LED (see board's front panel header pinout — usually bottom-right corner of board). Use the Define 7's bundled connector block if included.
Front USB headers — USB 3.0 (blue 19-pin) and USB-C (USB 3.2 Gen 2 header, if board has one)
Front audio header — HD Audio connector to board's AAFP header
Case fan headers — three case fans to CHA_FAN1–3
The front panel connectors (power SW, reset SW, LEDs) are the fiddliest part of any PC build — the pins are tiny and unmarked on the connector itself. The board manual's pinout diagram is essential. Get a torch and magnifier if needed.
8
Cable management — bundle and route
Behind the motherboard tray
Route all excess cable length behind the tray using the Define 7's tie-down points and velcro straps
Bundle the 24-pin ATX cable (the thickest) behind the tray before closing the back panel
Coil the SATA chains neatly in the PSU shroud area
Ensure all cables in the main chamber are routed away from the GPU and CPU cooler fan paths
9
Final inspection before first boot
Both sides of the case
Do not close the side panels yet — leave the case open for first boot
Do a visual sweep with a torch: no loose cables near fans, no cable ties left inside the main chamber, all connectors firmly seated
Connect monitors to the GPU outputs (not the motherboard rear panel)
Connect the mains lead to the PSU, flip the PSU switch to On

Cable Management — Define 7 Specifics

24-Pin ATX — Route First
Before the motherboard goes in, thread the 24-pin cable (already attached to the TX550M) up through the main PSU grommet hole on the right side of the tray. It's thick and stiff — threading it after the board is seated is genuinely difficult. Leave slack on the front-facing side.
EPS Cable — Top Routing Hole
The Define 7 has a dedicated cable routing cutout near the top-rear of the tray for the EPS CPU power cable. Use it. If you route the EPS cable in front of the tray (over the board), it will run through the NH-D15 G2's fan zone and be visible through the side panel.
SATA Cables — Right-Angle End at Drive
SATA data cables come with one straight and one right-angle connector. Always put the right-angle (L-shaped) end at the drive — it sits flush against the drive bay and won't stress the connector under vibration. The straight end connects to the motherboard's SATA ports.
Unused Modular Cables — Stay in the Bag
Store the TX550M's unused modular cables (extra PCIe, Molex) in the Corsair cable pouch, not stuffed inside the case. Excess cabling inside the case reduces airflow through the PSU shroud and makes future maintenance harder.
Fan Cables — Keep Them Short
The Define 7's three included fans have long cables (to reach any header position). Bundle excess fan cable length behind the tray or tuck it into the PSU shroud. A fan cable flopping near the front fan blades will eventually contact them, producing a rhythmic clicking noise.
Front Panel Headers — Use a Connector Block
If the Define 7 includes a front panel connector block (some versions do), use it — it groups the individual power/reset/LED wires into a single keyed plug that's much easier to install on the board header. If not included, use needle-nose pliers to seat the tiny individual connectors one at a time.

Pre-Power-On Checklist — Check Before You Press the Button

Power Connections
24-pin ATX latched: Press the connector until the plastic latch snaps into the retention tab on the board. A half-seated 24-pin is the #1 cause of "no POST" on first builds.
8-pin EPS (4+4) seated: Both halves of the 4+4 cable clipped together, fully inserted into the CPU power header. The system will power on without it but the CPU will immediately throttle or refuse to boot.
GPU PCIe power: If the RTX 3050 LP has a power connector, it is plugged in. If no connector exists on the card, nothing to connect here.
SATA power to both drives: Both 2.5" drives have a SATA power connector seated (L-shaped end firmly in, no crooked insertion).
PSU switch on: The rocker switch on the PSU rear panel is in the On (—) position, not Off (○).
Components
CPU lever fully closed: The LGA1700 socket lever is latched down and the CPU retaining arm is locked. An improperly latched lever prevents POST.
RAM in A2+B2 slots: Both 32GB sticks seated in the correct dual-channel slots (check board silkscreen — typically the 2nd and 4th slots from the CPU). Both clips clicked on both sides.
GPU PCIe retention clip: The clip at the end of the x16 slot has engaged — you should have heard it click during installation. The card should not rock or lift at the card-end.
CPU cooler mounted securely: No visible gap between cooler base and CPU IHS. All four mounting screws tightened in X-pattern. Cooler does not wobble when gently nudged.
NVMe drive screw tight: M.2 retaining screw in place — a loose NVMe may not be detected at boot.
Cables & Connectors
Front panel connectors: Power switch, reset switch, power LED, HDD LED all connected to the correct pins (verify against board manual). Incorrect power switch wiring means the power button won't work; incorrect LED wiring is cosmetic only.
SATA data cables: Both drives have SATA data cables connected from drive to motherboard SATA port. Not connected to conflicting ports (check M.2 slot SATA sharing in board manual).
CPU_FAN header connected: At least one of the CPU cooler fans is connected to the CPU_FAN header. Most boards refuse to POST or show a warning if CPU_FAN reads 0 RPM.
No cables near fans: Visual sweep confirms no loose cable ends in the path of any rotating fan. Spin each fan briefly by hand to confirm nothing is snagging.
Display
Monitors connected to GPU: All three monitor cables go into the RTX 3050 LP's outputs on the rear of the case — not into the motherboard's rear I/O HDMI/DP ports. The board's video outputs are disabled when a discrete GPU is present.
Monitor input source selected: Each monitor is powered on and set to the correct input source (DisplayPort or HDMI) matching the cable you've plugged in. An inactive input source shows "No Signal" even if the GPU output is working.
Final Steps
Side panels off for first boot: Leave both side panels off until you've confirmed the system POSTs and enters BIOS. Having quick access to cables and components is invaluable during troubleshooting.
Anti-static precautions done: You have touched the PSU chassis or a grounded metal object before handling components — your static charge is discharged. The TX550M chassis is a reliable grounding point throughout the build.
If it doesn't POST on first power: The most common first-boot failures in order of frequency: (1) 24-pin not fully latched, (2) RAM in wrong slots or not fully seated, (3) RAM needs XMP enabled, (4) front panel power switch wired to wrong pins, (5) GPU not seated and retention clip not clicked. Work through these before suspecting a dead component.
Next: Type PC11 to generate Chapter 11 — First Boot & BIOS Setup, covering what to expect when you power on for the first time, the critical BIOS settings for this build (XMP, CPU power limits, fan curves, boot order), and how to navigate an MSI/ASUS B760 UEFI.