Power supplies and cabling

The CMP 170HX takes all its power through one EPS12V socket. Most failures in the Discord came from feeding that socket wrongly: one PSU cable split two ways, pigtails, thin adapters, or a modular cable from a different PSU brand. Read the rules below before you plug anything in. Burned and failed hardware is collected under Power and cabling warnings.

The power input

• Proven The card has a single EPS12V 8-pin socket (the "CPU 8-pin": 4x 12 V and 4x ground), not a PCIe 8-pin. The pinouts differ even though the plugs look alike. Source: @wakeupmbrc1, 2026-10-09
  Source: @civiloid, 2026-10-15
• The 2x PCIe 8-pin to EPS adapter that comes with many cards is not for redundancy: the card draws through both inputs, each feeding half of the socket. Source: @reala7096, 2026-10-15
  Source: @civiloid, 2026-10-15
• Proven A CPU (EPS12V) cable straight from the PSU works and needs no adapter. Source: @analyticeth, 2026-10-09
  Source: @ropuls, 2026-10-09 Plug it into a PSU output labelled PCIe/CPU (or CPU). Source: @reala7096, 2026-10-15 Corsair's "CPU 8-pin" and EPS differ only in the width of the locking tab. Source: @civiloid, 2026-10-15
• The latch: most EPS cables have the double-width 4+4 latch (for compatibility with old 4-pin EPS boards), which does not clip onto the card. Trim it with a bandsaw or a rotary tool. Source: @civiloid, 2026-10-09
  Source: @ropuls, 2026-10-09
  Source: @c133, 2026-10-19 EPS-to-EPS cables bought from Amazon or PC Case Gear also needed "5 minutes with a dremel" to fit Source: @zarquon3157, 2026-10-27; @danske1 bought eight EPS-to-EPS cables (with a Gigabyte chassis) from an eBay Australia seller. Source: @danske1, 2026-10-27
• Right-angle adapters are only sold in PCIe form: a SinLoon PCIe right-angle extension "won't fit; you need a PCIe to CPU 4+4 cable", so @boz._. is splicing one onto an EPS cable. Source: @boz._., 2026-10-15
  Source: @reala7096, 2026-10-15

Cable rules

1. One EPS cable per card, straight from the PSU. This is the simplest and safest option. Source: @jjb01957, 2026-10-19
   Source: @.henrykrinkle, 2026-10-19
2. Or two completely separate PCIe 8-pin cables into the two inputs of the PCIe-to-EPS adapter. Every adapter input needs its own cable back to the PSU. Source: @c133, 2026-10-19
   Source: @endsjeremy, 2026-10-19
3. Never plug one PSU cable into both adapter inputs, and never use the 6+2 pigtails that hang off a PCIe cable for anything else. Source: @endsjeremy, 2026-10-18
   Source: @con3po7016, 2026-10-19 This is not about PSU wattage: "other users here have already proven that this is not safe". Source: @c133, 2026-10-19 @froggao ran a Corsair RM1000e with one 8-pin to dual 8-pin cable and said it worked; the group's answer was that poor wires, poor contact and high power limits combine, and that separate cables are required, not just safer. Source: @froggao, 2026-10-19
   Source: @wakeupmbrc1, 2026-10-19
   Source: @endsjeremy, 2026-10-19 The opposite advice was given earlier in the same thread: @squishysquare said he would be comfortable using both the 8-pin and the 6+2 pigtail of one cable for one EPS adapter (but would not run the 300 W VBIOS); the posts above, from the next day, advise against exactly that. Source: @squishysquare, 2026-10-18
   Source: @squishysquare, 2026-10-18
4. Never use 6-pin to 8-pin adapters. A 6-pin carries the same three 12 V terminals as a 6+2, but its cable is not built for the load. Source: @wakeupmbrc1, 2026-10-17
   Source: @civiloid, 2026-10-18 Use two 6+2 cables into the EPS adapter or build proper EPS cables. Source: @neapopa, 2026-10-17
5. Meter the PSU side before you use a cable from another brand. Modular connector housings fit across brands while the pinout does not: on an ASRock PG-1600G the side opposite the latch is all +12 V and the latch side is all ground, the reverse of a Corsair-compatible pinout, so a Corsair-type cable would have put +12 V on ground. Source: @c133, 2026-10-19
   Source: @globalapathy, 2026-10-19 The wrong pinout will likely kill a 170HX. Source: @c133, 2026-10-19 PixelML's rule: never mix modular cables between PSU models, even when they fit. Source: repo github.com/PixelML/club-170hx by PixelML on GitHub, posted by @c133, 2026-10-20 (Apache-2.0 license)
6. Use 16 AWG wire and good contacts; crimp quality and wire gauge are the limit, not the connector shape. Source: @wakeupmbrc1, 2026-10-19

Ready-made and custom cables:

• Corsair Type 4 PSUs (for example RM850x, not the RMx Shift): Corsair CP-8920141 sleeved 8-pin (4+4) EPS12V cable, PSU to card, but its 4+4 latch does not fit the card cleanly. Source: @c133, 2026-10-19
• @c133 builds Type 4 EPS cables from 16 AWG stranded copper and genuine Molex Mini-Fit Jr housings, cheaper than Corsair's if you own crimpers, and offered to make some for confirmed Type 4 PSU owners. Source: @c133, 2026-10-19
• Server PSU breakout boards: two 6-pin to EPS splitters per card have worked for years for @finishtilt14 Source: @finishtilt14, 2026-10-15; @backwardsminer had custom-length cables made, measured the current per pin and doubled the lowest-draw pins Source: @backwardsminer, 2026-10-15.

Connector ratings

Contested Posters quote different numbers; the differences are spec rating against what the terminals carry.

Connector	Numbers posted	Source
PCIe 6-pin	65 W rating; three 12 V terminals of 9 A minimum each, the same terminals as a 6+2	Source: @civiloid, 2026-10-17 Source: @wakeupmbrc1, 2026-10-19
PCIe 8-pin (6+2)	150 W rating Source: @civiloid, 2026-10-17; "about 175 W" per cable in practice Source: @endsjeremy, 2026-10-18	see cells
EPS12V 8-pin	235 W Source: @civiloid, 2026-10-15; "about 330 W" Source: @civiloid, 2026-10-17; 300 W continuous, the margin above is for transients Source: @endsjeremy, 2026-10-19; 300 W rated, 400 W peak, about 600 W possible Source: @endsjeremy, 2026-10-11; four 12 V terminals of 9 A or more, at least 432 VA Source: @wakeupmbrc1, 2026-10-19	see cells
18 AWG wire	10 A at 60 C, so about 360 W on a 6-pin's three 12 V wires	Source: @_arcanum_, 2026-10-15
12VHPWR terminal (for comparison)	rated "8a each or so"; the PCIe ATX 2.0 terminals above are about twice the size and four times the cross-section	Source: @wakeupmbrc1, 2026-10-19 Source: @wakeupmbrc1, 2026-10-19

• A single EPS12V feeds even the A100 PCIe at its 300 W factory limit; the slot supplies only a small share (a guess of about 25 W). Source: @wakeupmbrc1, 2026-10-19
• The PCIe 8-pin has its grounds reversed relative to the EPS 8-pin. Source: @endsjeremy, 2026-10-11

Burned and failed hardware

Each of these has its own entry, with the full thread, on Power and cabling warnings and Troubleshooting.

• Warning PSU burned after 48 hours at about 220 W per card on a DeepCool PX1000P, running cards from one PCIe cable each; the owner did not know each card needs two. The PSU protected the card. Source: @con3po7016, 2026-10-11
  Source: @endsjeremy, 2026-10-11 The PSU model rates well on a community PSU tier list, so the cabling was the cause. Source: @globalapathy, 2026-10-11 "Cheap out on the gpu not the psu." Source: @con3po7016, 2026-10-11
• Warning Magic smoke from powering a card through one cable plus its pigtail. Source: @con3po7016, 2026-10-19 A PSU shut down under load when an RTX 3090 was fed the same way. Source: @xeax, 2026-10-18
• Warning A 6-pin to 8-pin adapter melted at 170 W within weeks, one of six on HP server PSUs with hard-wired 6+2 leads. Source: @neapopa, 2026-10-17
• Warning A refurbished HP 1,200 W server PSU exploded with a loud bang after about two hours: three of them fed ten cards capped at 160 W, with GPU peaks near 2,000 W (55 % of rated capacity), during a 30-minute thermal bench then long-prefill GLM-5.3 work. The PSU fans never spun up and the units were very hot. Cards and system survived. Source: @reala7096, 2026-10-20 Capacitors in those PSUs "go bang" Source: @sojun80, 2026-10-20; test used PSUs on a CRPS tester away from your GPUs Source: @endsjeremy, 2026-10-20.
• Warning Aged breakout boards: constant reboots and PSU shutdowns under load came from server PSU breakout boards that failed after 3 to 4 years, not from the PSUs (the owner had bought six PSUs). The failed boards were ZSX-AMPS; he replaced them with X11-AMPS. Source: @finishtilt14, 2026-10-15
• Reported A Lian Li 1200G PSU shut down after a few hours at about 600 W because its quiet fan curve let it overheat; a USB fan on the PSU grille kept it running. Source: @phoenixone7, 2026-10-05 Another member called that not normal and suspected the fan. Source: @squishysquare, 2026-10-06
• Warning The 300 W VBIOS: a photo of a burned 170HX was posted earlier, and the board lacks some power-delivery parts of the full layout. Source: @xanthefin, 2026-10-18 See Undervolting and power limits.
• Reported 12VHPWR (not CMP-specific, relevant if you adapt such a PSU): connectors degraded twice on an RTX 5090 at no more than 70 % power, close to burning; another member's 12VHPWR terminal turned yellow. Source: @endsjeremy, 2026-10-17
  Source: @wakeupmbrc1, 2026-10-17

PSU sizing

Size for the CPU, board, fans and every card's cap, plus margin for spikes. Source: repo github.com/PixelML/club-170hx by PixelML on GitHub Short spikes go well above the cap: up to 380 W on cards capped at 250 W. Source: @n2dcrypt, 2026-10-05 @reala7096 worked out that nine cards spiking to 350 W together would need 3,000 W, but in a PP8 layout only about half the cards are busy at once. Source: @reala7096, 2026-10-05

Cards	Cap	Power supply	Result	Status	Source
4	300 W	one 1,600 W PSU	no shutdowns	Reported	Source: @okrasit., 2026-10-05
8	not given	two 1,600 W PSUs	no shutdowns yet	Reported	Source: @n2dcrypt, 2026-10-05
4	180 W	one used 1,200 W PSU (about $50)	bought for it	Reported	Source: @voidgiraffe, 2026-10-06
4	not given	whole system	up to 1,500 W at the wall	Reported	Source: @quark2world, 2026-10-04
2 CMP + 4 RTX 3090, no power limits	none	two ASRock PG-1600 (sold as Gold, tested Platinum by third parties), each on its own 20 A 120 V circuit	runs	Reported	Source: @zombielurker, 2026-10-05
4	175 W	two 750 W PSUs, two cards each, joined by a 24-pin Y adapter	all four cards and the PCIe switch lose power at once during heavy prompt processing	Reported	Source: @replacedriver47, 2026-10-05
9	160 W	three 750 W PSUs (2,250 W)	all cards drop about once a day	Reported	Source: @reala7096, 2026-10-05
10	160 W	three refurbished 1,200 W server PSUs	one exploded (see above)	Warning	Source: @reala7096, 2026-10-20
8	160 to 250 W (governor)	the server's own redundant PSUs on a 240 V circuit	runs; about 2.0 kW at 250 W caps	Reported	Source: @darkmaniac7, 2026-10-27 (lab notes)

• Proven About four cards per 1,600 W PSU works: four cards at a 300 W cap on one 1,600 W PSU with no shutdowns Source: @okrasit., 2026-10-05, and eight cards on two 1,600 W PSUs Source: @n2dcrypt, 2026-10-05.
• With several independent PSUs, one tripping on a spike can take down everything on a PCIe switch board. Source: @reala7096, 2026-10-05 A hot PLX switch chip can also drop cards. Source: @zombielurker, 2026-10-05 See Troubleshooting.
• PCIe switch boards need their own 24-pin and EPS power. Source: @gnasherrr, 2026-10-21
• Warning A fully SM-unlocked 10 GB card spiked to about 400 W at a 250 W limit. @djpandaman's 10 GB card, unlocked to 122 SMs, briefly reported about 400 W of board power during benchmark tests with the power limit set to 250 W; he was not sure whether the value was measured or calculated. @xeax recalled him mentioning about 375 W at a 250 W limit earlier. @xeax is weighing whether to fit the 6 MOSFETs missing from his own card's VRM, because he fears overloading the ones that are fitted, and doubts he could cool that load. Safe power limits for fully SM-unlocked cards are not known. Until they are, do not count on the cap to bound peak draw on such a card: size the PSU for the spikes, keep one EPS cable per card (rules above), and undervolt rather than raise the limit (see Undervolting and power limits#10 GB cards). The card's own power reading above 80 SMs is also reported to be unreliable; see 10 GB card#Limits. Source: @xeax, 2026-10-23
  Source: @xeax, 2026-10-23
  Source: @xeax, 2026-10-23
  Source: @djpandaman, 2026-10-23

Where to get power cheaply

• Contested Used ATX PSUs: @zorg33, who sold hundreds in the mining era, says 9 in 10 used ATX units are degraded and may hold only half their rating; test one near its rating for a few hours. His recipe: a small new quality PSU for the motherboard, and decommissioned 1,600 W Platinum server PSUs (about $20) for the cards, with custom EPS cables or adapters. Source: @zorg33, 2026-10-06 @ob88594 suggests used EVGA 1600 T2/G2 units. Source: @ob88594, 2026-10-06
• HP DPS-1200SB server PSUs with a cheap breakout backplane: about $50 each, 2,400 W for $150, quiet at 40 % load. Source: @reala7096, 2026-10-05 (Compare the exploded refurbished HP unit above.)
• Reported Most server PSUs derate to about half power on 120 V and need 220 to 240 V for full output. Source: @endsjeremy, 2026-10-21 C-Payne sells CRPS breakout boards (c-payne.com). Source: @endsjeremy, 2026-10-21 Some cheap ATX units go up to 3,000 W. Source: @endsjeremy, 2026-10-21
• Two PSUs in one box: use a PSU sync board. Source: @wakeupmbrc1, 2026-10-19

Wall power

• Plan circuits before you scale. @gpmickey added three 115 V 20 A breakers for twelve cards Source: @gpmickey, 2026-10-20; @con3po7016 cleared two circuits for his Source: @con3po7016, 2026-10-11; @zombielurker gives each PSU its own 20 A 120 V circuit Source: @zombielurker, 2026-10-05.
• Reported 240 V: the two hots are out of phase and need no neutral, only ground. Use a two-pole breaker with a hot on each pole and the existing ground if it is large enough; 12 AWG for a 20 A 240 V circuit. Use a non-contact voltage tester (the one @endsjeremy linked) every time: the work is simple but dangerous. Source: @endsjeremy, 2026-10-20 If in doubt, hire an electrician. Source: @endsjeremy, 2026-10-20 Ivan's eight-card server and its UPS run on a dedicated 240 V circuit. Source: @darkmaniac7, 2026-10-26 (lab notes)
• A whole-panel surge protective device (the one @endsjeremy used, about $60) snaps in like a breaker with a wire to the ground bar and shunts lightning, transformer and large-load surges to ground; its green light goes out when it is spent. The cheapest protection there is. Source: @endsjeremy, 2026-10-20
• Contested UPS: no UPS above about 1,600 W can go on a normal household outlet; larger ones need a 20 A receptacle. Tripp Lite (Eaton) is a safe choice; replace lead-acid batteries on principle. Source: @endsjeremy, 2026-10-21 @sojun80 prefers portable power stations (Anker SOLIX S2000, about $600) and says the transfer time must be under 30 ms; Anker and a few others do 20 ms or less. Source: @sojun80, 2026-10-21

See also

Power and cabling warnings · Troubleshooting · Cooling and power · Undervolting and power limits · Chassis builds · Platforms

Imported from the cmpunlocker Discord with credit; see Credits.