Installation_
The GPU Deployment Site Survey: What to Measure Before You Commit
This article details the exact measurements and verifications required in a pre-deployment site survey for H100 through GB300 NVL72 GPU racks, covering power, cooling, pathways, and access to prevent installation delays and rework.
Key facts
- NVLink GPU-to-GPU traffic in NVL72-class racks travels exclusively over internal copper spines or backplanes, while MPO-terminated fiber carries only the scale-out InfiniBand or Ethernet fabric.
- TIA-942 provides the tiered data center design framework that operators reference for redundancy levels in power and cooling distribution.
- ASHRAE TC 9.9 supplies the thermal guidelines for liquid-cooled IT equipment that determine required facility chilled-water temperatures and flow rates.
- Factory-terminated MPO trunks require cleaning and inspection with a calibrated scope before mating; field termination of MPO ferrules is not performed on site.
- Floor loading calculations must account for fully populated liquid-cooled racks plus coolant manifolds and must be verified against the structural engineer's stamped drawings.
- Clearance requirements around racks include both front and rear service aisles sized to allow removal of the heaviest field-replaceable unit without tilting the rack.
- Phase rotation and voltage at each whip must be verified with a calibrated meter before any GPU rack is energized to avoid damage to power supplies.
Power distribution and capacity verification
Measure available breaker positions, whip lengths, and connector types at each planned rack location. Record actual voltage, phase rotation, and available amperage under load using a calibrated three-phase meter. Compare these values against the OEM rack power specifications before any equipment is ordered.
Confirm that the upstream UPS and PDU infrastructure can sustain the sustained draw of a fully populated rack plus the inrush of the power supplies. Note any shared circuits or downstream panels that could create single points of failure. Document the results with photos and meter readings so the electrical contractor can correct deficiencies before rack delivery.
Leviathan Systems crews routinely find that nominal panel schedules do not match actual installed hardware; the survey catches these mismatches early.
Coolant and liquid cooling infrastructure readiness
Verify the presence, diameter, and pressure rating of facility chilled-water supply and return lines at each row. Measure available flow rate and supply temperature at the point of connection and compare against the rack manifold requirements supplied by the GPU OEM. Record isolation valve locations and confirm they are accessible after racks are installed.
Check that drip pans, leak detection, and drainage paths are already in place beneath the planned rack footprints. Note any elevation differences that would require additional pumps or elevation changes in the manifold piping. These measurements determine whether the facility loop can support the target rack density without supplemental cooling units.
Cable pathways, conduits, and overhead infrastructure
Walk every planned fiber and power route and measure conduit fill, bend radii, and pull-box access. Confirm that MPO trunk cables can be routed without exceeding the minimum bend radius specified by the cable manufacturer and that sufficient slack exists at both ends for patching. Identify any shared pathways that will carry both power and fiber and note required separation distances.
Document ladder rack or basket tray loading and available vertical space above each rack for the NVLink copper spines and scale-out fiber trunks. Record any obstructions such as fire suppression piping or HVAC ducts that would interfere with cable installation or future maintenance.
Physical access, floor loading, and rack placement
Measure door widths, elevator capacities, and corridor turns from the loading dock to the final rack position. Verify that the raised-floor or slab loading rating, including point loads from casters during installation, meets the structural drawings. Confirm aisle widths allow full rack rotation and removal of the heaviest FRU without tilting.
Record the exact location of each rack footprint relative to under-floor or overhead utilities so that manifold connections and power whips align without field modifications. Note any expansion joints or seismic bracing that could affect final rack leveling.
Scale-out fiber and MPO infrastructure survey
Locate the planned switch positions and measure the exact distances for each MPO trunk run. Confirm that patch panels are already installed with the correct MPO adapter types and that polarity matches the planned transceiver layout. Inspect existing trunks for damage and schedule cleaning and end-face inspection with a calibrated scope before any new connections are made.
Separate the survey of MPO fiber paths from any NVLink copper work; the two domains remain physically and electrically isolated inside the rack. Record port counts and available trunk strands so that scale-out capacity can be validated against the network design.
Common failure modes identified during site surveys
The most frequent issue is understated power draw caused by using nameplate ratings instead of measured or OEM-specified sustained loads; this leads to breaker trips after burn-in. Another common problem occurs when conduit fill or bend-radius violations are discovered only after trunks are pulled, requiring re-pulling or new pathways.
Floor loading miscalculations often surface when the structural engineer’s drawings are not reconciled with the actual slab rating, forcing last-minute rack relocation. Liquid cooling surveys frequently miss isolation valve accessibility once racks and containment are installed, creating service delays.
Leviathan Systems requires a second surveyor to re-measure any dimension that deviates from the drawings; this cross-check prevents the majority of these field changes.
Standards referenced: TIA-942 · ASHRAE TC 9.9 · TIA-568 · ISO/IEC 11801
Frequently asked_
How far in advance of rack delivery should the site survey occur?
Schedule the survey after the facility has reached final power and cooling configuration but before any GPU hardware is ordered. This timing allows electrical and mechanical corrections to be completed without delaying the deployment schedule. A follow-up verification walk is performed two weeks before delivery to confirm that all noted deficiencies have been resolved.
Do we need to survey NVLink connections separately from the MPO fiber plant?
Yes. NVLink traffic stays on internal copper backplanes within the rack; the MPO survey covers only the scale-out InfiniBand or Ethernet fabric between racks and switches. Mixing the two domains during the survey creates incorrect assumptions about required cable types and testing procedures.
What documentation should be produced from the survey?
Deliver a marked-up floor plan, measured power readings with meter serial numbers, coolant flow and temperature data, conduit and pathway photos, and a deficiency list with responsible parties. Include the structural engineer’s floor-loading confirmation and any required deviation approvals. This package becomes the basis for the final installation work package.
Who typically participates in the survey from the deployment team?
A power specialist, a liquid-cooling technician, a structured-cabling lead, and a rigging coordinator walk the site together. Each discipline records its own measurements on a shared template so conflicts between power whip locations and coolant manifolds are identified immediately. The combined report is reviewed by the customer’s facilities engineer before sign-off.
How are conduit and pathway measurements validated against actual install conditions?
Use a calibrated fish tape or pull string to confirm usable length and note every pull-box location. Compare recorded bend radii against the cable manufacturer minimums listed on the reel. Any deviation triggers a re-route decision before trunks are ordered.