THE UPGRADE WORKBENCH
What could stop your upgrade?
Start with the part you want to keep, the part you want to change, and the check that connects them.
START WITH YOUR UPGRADE
Choose the check that matches your upgrade.
01 / KEEP OR REPLACE?
Check your existing power supply first.
A wattage calculation can show a capacity shortfall. It cannot approve a particular PSU or its cables. Enter the exact-card recommendation when you have it.
Where do I find the inputs?
- Photograph the PSU label: full model, revision and continuous wattage. Do not open the PSU enclosure.
- Open the exact GPU model’s manual, not just a chip-family page. Find board power, recommended system PSU and the allowed power-cable arrangement.
- Find the configured CPU package-power limit. Base TDP alone may not describe turbo operation.
- The 75W field is an editable example allowance, not a measurement. Include pumps, drives, fans and other powered components.
No automatic “buy a PSU” verdict: being below our optional 25% sizing target is different from being below a supplied manufacturer requirement. A cable mismatch blocks the upgrade even when wattage looks sufficient.
Worked example: 650W PSU, 250W GPU, 140W CPU
With a 75W supporting-component allowance, estimated draw is 465W. A 25% allowance gives 581.25W. If the exact card’s manual recommends 650W, a 650W PSU meets those capacity inputs. Its model, condition and approved cables still need checking.
NVIDIA’s RTX 5070 Founders Edition manual allows the supplied adapter with two independent dedicated PCIe 8-pin cables, or a rated PCIe Gen 5 16-pin cable. That is specific to that card; a new ATX 3.x PSU is not automatically required for every RTX 40/50 card. Read the FE manual.
Check modular cable compatibility · Itemize the other components · Browse sourced GPU power profiles
02 / THE EXACT CARD MATTERS
Will the GPU fit with your cooling and cables?
“RTX 5070 Ti” is a chip family, not a set of dimensions. Identify the full card model, case revision and layout before comparing.
- Card envelope: manufacturer length, height and thickness in millimetres.
- Usable case space: the limit for your actual spine position, drive cage and front-cooling arrangement. Do not subtract a radiator twice from an already adjusted limit.
- Connector space: guidance for the exact cable and connector orientation. A generic bend-distance estimate cannot verify it.
The clearance checker reports each dimension separately. Missing cable space stays unverified. Its separate length worksheet can compare an explicitly documented cooling layout, but it cannot discover radiator interference or predict airflow.
Check card dimensionsTerra: GPU space versus CPU-cooler space · A4-H2O: radiator stack clearance
03 / A WORKLOAD, NOT JUST A MODEL SIZE
How much VRAM does your local LLM need?
Choose the exact model configuration and quantization, then set context length and cache precision. The calculator separates weights, KV cache and an editable runtime allowance.
- What will run? Exact text model and file format, not only “8B” or “70B”.
- How will it run? Context, cache type, runtime and memory already in use.
- What result do you need? Estimated memory margin. Fitting in memory does not predict response speed.
This estimate covers one text sequence on one GPU with weights in GPU memory. ComfyUI, multiple users, offloading and multi-GPU layouts need different checks.
Estimate model + context memoryFollow the worked memory calculation · Using ComfyUI instead?
04 / SUPPORT BEFORE SHOPPING
Can you keep the motherboard for a CPU upgrade?
A matching socket is the first check. You also need the board’s exact model and PCB revision, installed BIOS, CPU support-list entry and the manufacturer’s update procedure.
If any of those are missing, BIOS compatibility remains unknown. Do not infer it from the chipset name or let an AI invent a BIOS version.
Check the supported component recordsNeed a specific calculation?
Calculations run in your browser. No AI service or bot check is needed. Inputs are not submitted to an AI provider.