If your PC feels slow, don’t throw money at random parts. The smart move is to find the bottleneck first, then spend only where it removes the choke point. Below is a quick, repeatable process you can use to diagnose, prioritise, and upgrade on a budget.
Step 1: Diagnose the bottleneck (5 minute health check)
Run a game or app you actually use and watch these metrics (an in-game overlay or Task Manager is fine):
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CPU vs GPU usage
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CPU pegged (80–100%) while GPU sits <70% → CPU-limited.
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GPU at 95–100% with stable CPU headroom → GPU-limited (normal in many games).
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RAM usage
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If you’re above 85–90% of system RAM, Windows will page to disk → hitching and stutter.
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VRAM usage
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Near/full VRAM (8GB cards especially) → texture pop-in, stutters; lower texture settings or consider a higher-VRAM GPU.
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Storage activity
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Disk at/near 100% active time, especially on a hard drive → your storage is the clog.
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Temperatures / clocks
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CPU >90°C or GPU >85°C with dropping clocks = thermal throttling.
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Frame time spikes
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Smooth FPS but spiky frame times = RAM/VRAM pressure, storage stalls, or background tasks.
Example mismatch: RTX 3090 + 8GB RAM. The GPU can fly, but with only 8GB system RAM you’ll slam the pagefile and stutter like mad in modern titles. Fix the RAM before blaming the card.
Step 2: Match the symptom to the fix
If you’re RAM-bound
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Target 16GB minimum for general gaming; 32GB if you mod, multitask, or run heavy titles.
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Run dual-channel (2 sticks) and enable XMP/EXPO in BIOS so your RAM actually runs at the rated speed.
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Avoid mixing random sticks/brands if you can; matched kits usually reduces headaches.
If you’re storage-bound
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Ditch the HDD for your OS/games. A cheap SATA SSD is a night-and-day upgrade; NVMe is even snappier if you’ve got a slot.
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Keep 20–25% free space on your game drive to avoid performance dips.
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Move your heaviest games and scratch/cache folders onto SSD/NVMe.
If you’re VRAM-bound
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First aid: drop textures one notch and use DLSS/FSR/XeSS on “Quality”.
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Long term: consider a GPU step with more VRAM (e.g., 8GB → 10–12GB).
If you’re CPU-bound
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Lower CPU-heavy settings (crowds, view distance, shadows).
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Cap FPS to your monitor’s refresh (or a tidy multiple) to tame CPU spikes.
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If your board allows, a drop-in CPU upgrade can be of huge value—often cheaper than a platform swap.
If you’re thermally-bound
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Dust out the case, especially front intakes and heatsinks.
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Re-paste older GPUs/CPUs and replace tired thermal pads on memory/VRM where sensible.
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Add a front intake fan; re-arrange cables to open an airflow channel.
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Consider a GPU undervolt and saner fan curve for cooler, quieter frames.
If your PSU is the hidden villain
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Sudden shutdowns under load? Check the PSU’s age and rails.
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Use separate PCIe power leads for hungry GPUs.
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Prioritise quality over raw wattage; stability beats a cheap “bigger number.”
Step 3: Spend smart — budget ladders (UK-friendly)
£0–£25 “free speed”
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Enable XMP/EXPO, Resizable BAR/SAM (if supported).
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Update BIOS, chipset, and GPU drivers; kill startup bloat.
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Clean dust; re-route cables; set sensible fan curves.
£25–£60 “instant feel” upgrades
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500GB SATA SSD for OS + a couple of heavy games.
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One or two decent 120/140mm case fans (fresh front intake = free FPS).
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Thermal paste + isopropyl clean for 3–5-year-old CPUs/GPUs.
£60–£120 “unlock the rig”
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1TB NVMe as a primary game drive (if you have an M.2 slot).
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Bump 8→16GB RAM (matched kit), or 16→32GB if you multitask/stream.
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Better CPU cooler to stop throttling and noise.
£120–£200 “value big hitters”
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GPU step-up within a generation (e.g., more VRAM or a stronger tier).
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Drop-in CPU upgrade on the same socket, if your board supports it.
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Mid-range PSU from a reputable brand to support a future GPU.
£200–£400 “targeted transformation”
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Used GPU generational jump (with VRAM headroom) for 1080p/1440p.
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Board+CPU combo upgrade if you’re stuck on old cores/speeds.
Rule of thumb: Fix RAM/SSD/thermals first, then consider CPU/GPU. A new graphics card won’t shine if you’re still using a hard drive and cooking at 95°C.
Quick wins most old PCs are missing
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Dual-channel memory: two smaller sticks beat one big stick at the same total capacity.
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Game-specific settings: Textures, shadows, RT, and crowd density move the needle most.
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Upscaling: Quality-mode DLSS/FSR/XeSS gives you “free” FPS with minimal visual cost.
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Background hygiene: close launchers, overlays, RGB hubs, and browser tabs before gaming.
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Monitor match: cap FPS to your panel (or use VRR) to erase micro-stutter and reduce load.
Common mismatch checklist (fix these first)
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High end GPU + 8GB RAM → upgrade to 16–32GB + enable XMP/EXPO.
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High end GPU + tiny PSU (or daisy-chained single cable) → quality PSU + separate leads.
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Fast CPU + slow HDD → SSD/NVMe or it will still feel slow.
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Triple-fan GPU + cramped case → add front intake, move drives/cables, consider a shorter card.
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8GB VRAM + max textures at 1440p → lower textures or move to a higher-VRAM card.
How GPUsed can help (without overspending)
Tell us your CPU, motherboard, RAM (speed/size), GPU, PSU, case, and monitor plus your budget ceiling. We’ll:
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Spot the bottleneck from your symptoms/metrics.
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Propose a prioritised parts list (e.g., SSD + 16GB RAM now, GPU later).
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Supply tested, cleaned, and stress-checked used parts (GPUs, RAM kits, SSDs, PSUs).
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Include clear guidance for cables, BIOS settings, and fan placement so you see gains day one.
Summary -
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Measure first, then upgrade the exact choke point.
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The best £/performance usually comes from RAM, SSD/NVMe, and cooling, before big-ticket parts.
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Aim for 16–32GB RAM, SSD game storage, sane temps, and a right-sized PSU.
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When you’re ready for a bigger jump, pick a GPU with enough VRAM for your resolution and settings—and make sure the rest of the system won’t hold it back.
Want a personalised plan? Drop your specs and budget, and we’ll build a bottleneck-busting upgrade path that makes every pound pull its weight.
Published - Max Brocklesby - 19th September 2025