Water cooling

Water is the quiet option. The card's stock heatsink needs server-class airflow; a full-cover block on a loop runs silently at 45 to 60 C. It costs more than fans and you have to take the card apart, which on used cards usually means cleaning and new pads too.

Blocks that fit

The CMP 170HX uses the A100 PCIe board, so A100 40 GB PCIe water blocks fit. 3090 blocks do not. Source: @gnasherrr, 2026-10-14 Both the CMP 170HX and the A100 40 GB have an integrated heat spreader (IHS); the A100 80 GB does not, and its blocks have a raised cold plate for the bare die, so do not buy an 80 GB block. Source: @_arcanum_, 2026-10-20
Source: @spectakkular, 2026-10-27

Block	What people report	Price seen (October 2026)	Status
Bykski N-TESLA-A100-40G-SR (full copper)	The block most owners bought; "the ideal block" Source: @djpandaman, 2026-10-09; fits the newer CMP 170HX and the 170th Street install steps still apply Source: @lia_oc, 2026-10-10; eight cards in blocks on one build Source: @djpandaman, 2026-10-09	$160 per block from Bykski's official Taobao store Source: @djpandaman, 2026-10-08; under $180 delivered with a coupon Source: @rrickk420, 2026-10-05; $220 the cheapest another member found Source: @peter643, 2026-10-20; about $140 by contacting sellers directly (eBay names, phone, email, WhatsApp) and negotiating a larger order with one supplier, not through AliExpress, Alibaba or eBay, paying by PayPal or credit card; he would not buy from that supplier again Source: @_syn_thetic_, 2026-10-25; 8 for about $165 each, since roughly doubled Source: @_syn_thetic_, 2026-10-20 Source: @globalapathy, 2026-10-20	Proven
Bykski N-TESLA-A100-X-V2 (all-metal V2)	The block the 170th Street guide was written for: "only commercially available full-coverage waterblock confirmed compatible"; 45 C at 180 W on a 360 mm radiator with fans at minimum speed. Not the N-TESLA-A100-80G-X-V2 (different PCB), and not the older acrylic non-V2. Source: repo github.com/amoghmunikote/170th-Street by amoghmunikote on GitHub, posted by @markshowa, 2026-10-18 (no license stated)	not given	Reported
TinyWhale blocks	The same product as Bykski: TinyWhale is the brand in China, Bykski outside it (what a supplier told @_syn_thetic_) Source: @_syn_thetic_, 2026-10-25; "Bykski ones with a different top plate" Source: @_arcanum_, 2026-10-20. A Bykski box arrived with a TinyWhale logo on the block.	not given	Reported
"Alphacool" listings	@globalapathy ordered Alphacool and received TinyWhale Source: @globalapathy, 2026-10-20; @_arcanum_ says real Alphacool is not the same block Source: @_arcanum_, 2026-10-20	not given	Contested
Generic "RTX A100" labelled Ampere data-center blocks	Fitted to @gnasherrr's cards; fully compatible because the boards are the same Source: @gnasherrr, 2026-10-14	not given	Reported
Single-slot blocks	@djpandaman's eight cards use single-slot blocks that leave the NVLink fingers under the aluminium casing Source: @djpandaman, 2026-10-08; @gnasherrr's single-slot blocks cost about $200 shipped each because he buys directly on Xianyu and arranges the shipping himself Source: @gnasherrr, 2026-10-15; an Alphacool copper and carbon single-slot block (about 300 EUR) is out of production Source: @rh3dai, 2026-10-12	about $200	Reported

Coverage: does the block cool everything the stock heatsink did?

Contested

@_syn_thetic_ owns eight blocks and says they are A100 blocks with "170HX" added to the listing, not full coverage: the stock passive cooler has two heatsinks and actively cools the bottom LR22 chokes, DrMOS and capacitors, which the block leaves bare. His concern is longevity, not day-one temperatures. Source: @_syn_thetic_, 2026-10-20
@_arcanum_: the parts without contact are capacitors, which make little heat; the block cools the FETs next to them, which are what would actually fail, and the VRM is overkill for 250 W. Source: @_arcanum_, 2026-10-20
@leenodie runs the block at 250 W full load with 50 C maximum; only a small strip is uncovered and a thicker pad closes it. Source: @leenodie, 2026-10-26 @wakeupmbrc1 points out that you can only see the GPU and HBM temperatures, not the uncovered board parts. Source: @wakeupmbrc1, 2026-10-26
Ways people close the gap: copper and silicone pads Source: @zorg33, 2026-10-20; copper shims set in thermally conductive epoxy (Omega OB-101-2 was suggested) Source: @globalapathy, 2026-10-20; thermal putty on the backplate side, which @_syn_thetic_ judged not enough on its own Source: @_syn_thetic_, 2026-10-20; 2.5 mm pads on the back side behind the MOSFETs and on the inductors Source: @gnasherrr, 2026-10-25.

All-in-one coolers

Two dual-card AIO kits fit: the Bykski AIO for the Tesla A100 40 GB and A30 (B-FRD-TESLA-A100, formulamod), and the Astralcooler all-in-one server GPU cooler with a 360 or 480 radiator, sold as compatible with the CMP 170HX, A100 40 GB and A30. Source: @globalapathy, 2026-10-04 The Astralcooler is also sold on Amazon (B0HK47YZS2), which @globalapathy bought. Source: @globalapathy, 2026-10-10
Proven @civiloid moved four cards to a Bykski AIO for about $700 in total; the cards are now "cool and quiet". Source: @civiloid, 2026-10-13 For three or four cards, buy two dual AIOs and leave the fourth block unused. Source: @civiloid, 2026-10-16 @globalapathy runs two dual AIOs with 480 radiators for four cards in an EK-Fluid Works V3000 chassis (TitanRig), which holds two 480 mm radiators; a fifth card would need a case mod. Source: @globalapathy, 2026-10-18
Price: under $400 for the dual version on Taobao before shipping, list price 2,600 to 2,900 RMB Source: @_arcanum_, 2026-10-04; $250 per dual unit with a $100 Taobao coupon plus a Bykski discount, $500 for two shipped to Korea Source: @artistosu, 2026-10-04; formulamod and astralcooler.com add about $250 shipping to the USA Source: @globalapathy, 2026-10-04. Prices rose after the 170HX unlock. Source: @artistosu, 2026-10-04
Reported The radiator in the TinyWhale AIO version is aluminium while the block is copper. Source: @globalapathy, 2026-10-26 Mixing aluminium into a copper and brass loop invites galvanic corrosion; @_syn_thetic_ suggests a partial refund and a copper radiator. Source: @_syn_thetic_, 2026-10-20
Reported Cards sold already liquid-cooled. PJ (@zingy90210) bought CMP 170HX cards fitted with liquid coolers from a local seller in Sydney (photos posted); the seller can also do the water-cooling conversion for you. @danske1 had seen these coolers on eBay. @siriusrhi's objection: that style needs an AIO and a 240 mm radiator per card, so four cards means mounting four 240 mm radiators; he prefers a custom loop (see Chassis builds#Cases). Prices are on Buying#Prices as reported. Summary of their posts; see Discord. Source: @zingy90210, 2026-10-25
Source: @zingy90210, 2026-10-25
Source: @danske1, 2026-10-25
Source: @siriusrhi, 2026-10-25
Source: @zingy90210, 2026-10-25
An AIO-cooled card can run in a desktop with a riser cable or OCuLink from an M.2 slot, or with the radiator sitting outside the case. Check the PSU first. Source: @robbbbbb7973, 2026-10-18
Source: @globalapathy, 2026-10-18
Source: @boz._., 2026-10-18

Installing a block

The 170th Street "Watercooling Installation" page by Amogh Munikote (author of cmpunlocker) is the reference; the steps still apply to newer cards. Source: @lia_oc, 2026-10-10 Read it and its teardown page before you start: 170th Street: Watercooling Installation (no license stated, so this page only summarises it) Source: repo github.com/amoghmunikote/170th-Street by amoghmunikote on GitHub. The points that cause damage:

Warning Cover every unpopulated IC footprint under the block's contact pillars with thermal pad. Without it the block's metal shorts across the exposed copper pads; the guide calls this the most common way people damage the card. Source: repo github.com/amoghmunikote/170th-Street by amoghmunikote on GitHub
The stiff power cable pushes the block out of line. Fit one mounting screw, seat the power cable, then the other three. Source: repo github.com/amoghmunikote/170th-Street by amoghmunikote on GitHub Source: @lia_oc, 2026-10-10
Contested Washers: the guide reuses the four original GPU washers. @lia_oc disagrees on that step: use washers that are not the originals so the block makes proper contact. Source: @lia_oc, 2026-10-10
The backplate needs the card's PCIe bracket as a spacer or it can short. The included hex wrench is the wrong size; backplate screws are M2 9.5 mm. Never run the pump dry more than 5 minutes. Source: repo github.com/amoghmunikote/170th-Street by amoghmunikote on GitHub
Warning The block's power-connector retention cover clamps a cable that is too rigid for its opening and bent @gnasherrr's PCB slightly. Source: @gnasherrr, 2026-10-25 Leave the retention plate off; any PCB flex makes solder joints fail sooner with power cycling. Source: @_syn_thetic_, 2026-10-25
Warning Poorly machined block standoffs without dampers can cut the solder mask and short the board; with a PSU that does not trip fast the spot reaches 1,500 C in tens of milliseconds. Shown on a Radeon, not a 170HX. Source: @wakeupmbrc1, 2026-10-16 Many boards also lack the small fuses that would limit the damage. Source: @endsjeremy, 2026-10-16
@_syn_thetic_ puts Kapton tape around the power cables and solder areas, front and back. Source: @_syn_thetic_, 2026-10-25

Opening the card: cleaning, pads and paste

Proven Expect used cards to be dirty inside, with pads falling apart or missing: clean, repad and repaste when you open one. Source: @civiloid, 2026-10-11 Cleaning: isopropyl alcohol and a toothbrush Source: @squishysquare, 2026-10-11; old paste can be rock hard and need dental picks Source: @gnasherrr, 2026-10-25. Cards from Alifond arrived filthy, without pads on the back and on side components under the main heatsink, even though Alifond opens them for the capacitor mod before shipping Source: @_syn_thetic_, 2026-10-25; another buyer called the quality of his Alifond cards horrendous Source: @kellertreppe123, 2026-10-25. Cleaning kit suggested (not yet tried by the poster): ArctiClean Source: @_syn_thetic_, 2026-10-25.
Do you need to repaste? If the card is old (probe its hours used; thousands of hours means repaste) or runs hot. Source: @_orrorin, 2026-10-12 If temperatures are fine under long load at the fan speed you will run, a repaste typically gains about 2 C. Source: @vcore2191, 2026-10-12 @alanoo repasted one card with MX-7 and gained nothing. Source: @alanoo, 2026-10-16 @ghostinthedatacenter_87281 saw a large drop with a repaste and PTM on an 8 GB card (idle memory 37 C, against 41 C on a 10 GB card at the same 33 W). Source: @ghostinthedatacenter_87281, 2026-10-13
Disassembly is easy to get wrong: tilt the card out of the housing carefully. Source: @ob88594, 2026-10-12

Pad thickness

Contested Nobody has posted measured pad heights for every location. Measure yours before you order.

Location	Thickness	Source
HBM/VRAM area	2 mm (measured from PCB and die photos)	Source: @lenxtroz, 2026-10-13
MOSFETs / coils	2 mm / 1 mm	Source: @emogop, 2026-10-13
VRM, DrMOS, PMIC (water block)	1.5 mm, from the Bykski block instructions; T-Global TG-A4500 1.5 mm (DigiKey) chosen	Source: @markshowa, 2026-10-19
Block kit instructions vs listing	1.2 mm in one kit's instructions, 1.5 mm on its listing	Source: @globalapathy, 2026-10-12
Stock heatsink	1.5 mm (a YouTube comment); "all 2 mm" (hearsay); 1 mm and 0.5 mm also heard	Source: @con3po7016, 2026-10-16 Source: @trustinter, 2026-10-16 Source: @robbbbbb7973, 2026-10-21 Source: @markshowa, 2026-10-21

Ways around it: thermal putty instead of pads (Upsiren) Source: @civiloid, 2026-10-13, or liquid pads such as Laird 607 or Upsiren UTP-8 / UTP-X. Source: @wakeupmbrc1, 2026-10-16 Putty and pads conduct worse than paste; they are only better than air. Source: @civiloid, 2026-10-18

Die and IHS interface

The IHS is 46 x 46 mm (from memory), which answers the usual question of what size to cut PTM7950 Source: @fiiireface, 2026-10-06; most consumer PCM packs are smaller in one dimension. Source: @globalapathy, 2026-10-11
Phase-change material: Laird A18172-08 (TPCM 7000 class, DigiKey), about $36 for a sheet that covers about 10 cards, comparable to Honeywell PTM7950 and cheaper; freeze it before handling. Source: @globalapathy, 2026-10-11 PTM7950 is heavily counterfeited. Source: @globalapathy, 2026-10-18 Cut pieces from 50 x 50 mm sheets Source: @civiloid, 2026-10-11; Upsiren's PTM clone is a cheaper option Source: @civiloid, 2026-10-13. High-conductivity pads: Gelid TP-GP04-C (DigiKey), 1.5 mm, 15 W/m-K. Source: @globalapathy, 2026-10-11 @globalapathy ordered both for a refresh when @stormlrd. asked what pads to use on 20 cards; no results were posted yet. Source: @stormlrd., 2026-10-10
Source: @globalapathy, 2026-10-10
Contested @skirtchaser: PTM7950 is the only interface guaranteed to work on HBM dies, which are too uneven for paste or liquid metal Source: @skirtchaser, 2026-10-18; @civiloid: unevenness is not the problem since paste was there before, but a good PCM is close to liquid metal without its risks Source: @civiloid, 2026-10-18.
Warning Liquid metal is not recommended: it spreads, needs management, still dries out, and has shorted components. Source: @globalapathy, 2026-10-11
Source: @gpmickey, 2026-10-11
Reported Under the IHS is paste, apparently a phase-change material, not the indium solder you would expect on a part like this. Source: @wakeupmbrc1, 2026-10-12
Source: @globalapathy, 2026-10-12
Source: @gnasherrr, 2026-10-18
Source: @xeax, 2026-10-18 Old paste under the IHS is a large part of the thermal problem Source: @xanthefin, 2026-10-18, which limits what a repaste on top can do Source: @spectakkular, 2026-10-12.
Cleaning tip: after alcohol and brushing, a strip of Kapton tape on the IHS pulled off the last layer of old paste residue. Source: @_syn_thetic_, 2026-10-21
Warning Delidding: there have been accidental delids Source: @skirtchaser, 2026-10-18. The stock cooler cannot be used on the bare die without making up the IHS thickness or you cook the die, and it cannot be tightened further without damaging the VRM. Source: @civiloid, 2026-10-18 Theory @markshowa's idea: delid, solder a copper shim to the stock cooler and use PCM on the die, to run the HBM cooler and clock it higher; nobody knows the IHS thickness yet. Source: @markshowa, 2026-10-19 Theory On 2026-10-22 he added that the A100 80 GB PCIe (300 W TDP) has direct-die cooling, so a delidded 170HX with a ring like the A100 80 GB's should cool better by air or water. Counterpoint from @gnasherrr: heat transfer is almost never the bottleneck on a GPU because heat density is low, about 300 W over 826 mm², and that figure assumes the HBM gives off no heat. Nobody reported a delid attempt. Source: @markshowa, 2026-10-22
Source: @gnasherrr, 2026-10-23
Source: @gnasherrr, 2026-10-23

Loops

Block quality matters little at these powers. At 575 W and over 1.5 GPM (5.7 L/min) coolant rises about 1.5 C through a 5090 block, so at 175 W the rise is about 0.44 C and a premium block's 1 to 3 C edge is negligible. Source: @rrickk420, 2026-10-08 Bykski matched Watercool blocks within 0 to 0.5 C on a 575 W 5090 at 1.5 GPM and up. Source: @wakeupmbrc1, 2026-10-08
Radiators and pumps: a MO-RA IV 400 with 4x 200 mm fans is silent and runs on one D5; the MO-RA IV 600 needs two pumps; use Koolance quick disconnects for a detachable radiator. Source: @zaknafar, 2026-10-10 @wakeupmbrc1: a D5 is a poor pump for loops this size; use an Alphacool QX5, or two QX5 plus one or two D5. Source: @wakeupmbrc1, 2026-10-10 Also considered: the MO-RA IV 600 (9x 200 mm) and the Alphacool NexXxoS XT45 1080 mm Nova (9x 120 mm), all at TitanRig. Source: @globalapathy, 2026-10-10
Aluminium blocks exist too: an aluminium A100 block on eBay at about $450 ("robbery" to @_syn_thetic_); @_arcanum_ runs an all-aluminium loop, fittings and quick disconnects included, so the metals never mix. Source: @globalapathy, 2026-10-20
Source: @_arcanum_, 2026-10-20
Source: @_syn_thetic_, 2026-10-20
Contested Pumps for many blocks. The 2026-10-25 debate, in the order posted:
- @_syn_thetic_ (about 20 years of water-cooling): a D5 (about 4 m of head, 500 L/h) is the wrong pump for multi-GPU loops; it lacks pressure and flow, and DDC and QX5 tops are not enough either. His pump does 2,700 L/h with 28 m maximum head and 5 to 100 % PWM; at 40 % it gives much more flow and pressure than a D5 at lower cost, and it is silent. Source: @_syn_thetic_, 2026-10-25
  Source: @_syn_thetic_, 2026-10-25
  Source: @_syn_thetic_, 2026-10-25
  Source: @_syn_thetic_, 2026-10-25
  Source: @_syn_thetic_, 2026-10-25
- @wakeupmbrc1: these blocks usually drop under 0.7 psi each, so two DDC-type QX5 pumps in series are more than enough for 4 GPUs; add one or two D5s in parallel for more. Other solutions are louder. Source: @wakeupmbrc1, 2026-10-25
  Source: @wakeupmbrc1, 2026-10-25
  Source: @wakeupmbrc1, 2026-10-25
- @_syn_thetic_: more than 4 cards in a series plus parallel loop is not ideal, and with the cards fed in parallel from a distribution block a D5 is too weak. Source: @_syn_thetic_, 2026-10-25
@_syn_thetic_'s loop layout: 1/2 x 3/4 inch main trunks with compression fittings, 3/8 x 5/8 inch lines to the blocks, distribution fed from both channel sides (top block out, return the same way), and oversized ball valves in the right places instead of quick disconnects. Source: @_syn_thetic_, 2026-10-25
Source: @_syn_thetic_, 2026-10-25
Source: @_syn_thetic_, 2026-10-25
Source: @_syn_thetic_, 2026-10-25
Source: @_syn_thetic_, 2026-10-25
Parts and prices: @wakeupmbrc1 points to the vendor Iceman, which sells full CNC brass and copper D5 dual tops (about 2 kg) for 600 RMB retail, and DDC and QX5 tops too. Source: @wakeupmbrc1, 2026-10-25
Source: @wakeupmbrc1, 2026-10-25
Source: @wakeupmbrc1, 2026-10-25
Source: @wakeupmbrc1, 2026-10-25 @munisix guessed blocks at about 100 USD per card; @_syn_thetic_ answered that block prices are now far higher (see the table above). Source: @munisix, 2026-10-25
Source: @_syn_thetic_, 2026-10-25
About $350 buys a good GPU loop. Source: @wakeupmbrc1, 2026-10-17
Chillers: insulate the tubing so room air does not heat the coolant and the chiller runs less, and keep the loop just above the dew point so nothing condenses. Source: @gnasherrr, 2026-10-26 Do not bring cold winter air in for air-cooled cards either: condensation. Source: @alanoo, 2026-10-20
Reported @rh3dai runs at least 18 cards on a ground-cooled liquid loop at 230 W with +210 to +240 core offset at about 1,455 MHz; outlet coolant is kept at 30 to 31 C because the loop heats his house; noise at his desk is near zero. Source: @rh3dai, 2026-10-14

Results

Photos of a large stack of cards that look water-blocked were posted without details. Source: @feralzi, 2026-10-18
Source: @froggao, 2026-10-18

Setup	Power	Temperature	Source
Bykski-type block, full load	250 W	50 C max	Source: @leenodie, 2026-10-26
Bykski N-TESLA-A100-X-V2, 360 mm radiator, fans at minimum	180 W	45 C	Source: repo github.com/amoghmunikote/170th-Street by amoghmunikote on GitHub
Water-cooled cards in general	not given	"normal temps, 50 60c"	Source: @endsjeremy, 2026-10-20
Bykski AIO, four cards	not given	"cool and quiet"	Source: @civiloid, 2026-10-16
Ground-cooled loop, 18 cards	230 W	coolant out 30 to 31 C	Source: @rh3dai, 2026-10-14

Water cooling also gives room for a higher power limit and memory clock: @xeax says it lets you push the memory to 2 TB/s. Theory Source: @xeax, 2026-10-15

Custom and alternative coolers

Reported @rh3dai rebuilt the stock air cooler into a water block: he took leftover water blocks from RTX A4000 cards and milled them flat to sit on the 170HX, which cost him about $60 per block to modify. The result runs about 7 C above a proper full-copper Bykski block, better than air, but it cannot get better because the stock cooler has copper only over the core and aluminium plus heat pipes elsewhere. He made the video public (Czech, with ideas you can follow without the language): Rebuild GPU cooling block #CMP170HX - AIR block to WATER Block!. His advice afterwards: $160 for a Bykski block is a fine price; the time it took was not worth it. Source: @rh3dai, 2026-10-07
Reported @cmurrayis was designing a custom copper water block with a single-slot footprint together with an ex-Huawei thermal engineer. The engineer was badly injured in an accident; finishing the CFD alone would have cost about $1,500, and with community blocks at about $130 he stopped the project on 2026-10-12. The design was not finished, but he offered to share what he has (the relief map and the mounting information) with @spectakkular, who plans to machine his own blocks, probably in aluminium. A render of the design was posted. Source: @cmurrayis, 2026-10-04
Source: @spectakkular, 2026-10-12 @rh3dai's advice for any new design: make it single slot. Source: @rh3dai, 2026-10-12
Contested Cheap V100 SXM2 blocks ($30 to $50): the mounting holes are a bit off and the VRMs and caps sit differently Source: @djpandaman, 2026-10-05; @rrickk420 thinks a milled plate, a printed shroud and copper heatsinks could reach 90 % of a Bykski for $70 to $100 Source: @rrickk420, 2026-10-05; the aluminium plate makes no thermal contact with the water, so the power stages need more surface or airflow Source: @_arcanum_, 2026-10-07; @rh3dai found that kind of block not enough for 200 W and above Source: @rh3dai, 2026-10-07.
Theory Strip the fins off the stock heatsink and clamp a water block on the copper base (in progress). Source: @tekkenz, 2026-10-24
Theory Adapt a 600 W GPU AIO with a milled copper adapter brazed to its cold plate. Source: @endsjeremy, 2026-10-17
Theory A cheap RTX 4090 cooler shell as an active cooler (done on V100 and P100 PCIe cards), and a Corsair 240 mm AIO on a CMP 170HX with a flat plate, both from videos. Source: @djpandaman, 2026-10-22
Theory Machining your own block: a desktop CNC can get within a few degrees of big-brand blocks Source: @rrickk420, 2026-10-08; true microchannels need precise machining, but copying a working design is viable Source: @globalapathy, 2026-10-08.
Theory A milled solid heatsink or a custom heat-pipe air cooler (laser-cut fins, brazed copper heat pipes) for static-pressure air cooling. Source: @endsjeremy, 2026-10-06 Counterpoint: the stock heatsink is already large, copper and heat-piped, and 250 W continuous is hard to beat in two slots. Source: @djpandaman, 2026-10-06