igneum/docs/analysis/card-lifetime-2026-10-05.md

Card lifetime per tier: how many years a card keeps mining

5 October 2026. Consequences review, sub-agent of the consequences reviewer. Desk arithmetic only; nothing was run.

1. Inputs

Input	Source	Value used
Dataset schedule	docs/spec/01-lottery-hash.md 432 to 437	2 GiB at genesis plus 0.5 GiB a year (2,048 + 512 x years MiB)
Index mapping (a)	same file, line 442	multiply-shift: the dataset grows every day, continuous
Index mapping (b)	same file, line 442	power-of-two steps 2, 4, 8 GiB on the schedule's average: 4 GiB at year 4, 8 GiB at year 12; my extrapolation: 16 GiB at year 28, 32 GiB at year 60
Scratch per resident warp	igneum-wt-ca2-cache/docs/plans/hot-table.md 66 to 73	32 or 128 KiB per warp; 5090 = 170 SMs x 48 warps = 8,160 (approximate, from memory)
Hot table, buffers	same file, 70	hot table 32, 64 or 96 MiB (96 used here); buffers 128 MiB
Cache	hot-table.md 70 (resident, 256 MiB in every total) against igneum-wt-ca2-era/docs/plans/era-layout.md 93 ("resident only while the day's dataset is built, then free")	both readings carried: resident = worst case, freed = best case. The two plans disagree and gate 1 should say which
Cache growth	igneum-wt-ca2-coord/docs/plans/counter-asic-2-status.md 79 (layer 6 option C)	256 MiB at genesis, 512 MiB at year 4, 1 GiB at year 12; by the same rule 2 GiB at year 28, 4 GiB at year 60
Budget rule	same file, 17: the whole working set stays under 6 GB on an 8 GB card	my reading: 75% of card memory at every tier. Apple: 50% of unified memory, because macOS, the display and the node share it; that share is my assumption
Public claims	site/index.html 443, 461; site/litepaper.html 560; docs/evidence.md	quoted in Table 3. evidence.md has no row on card lifetime

Card memory is binary (8 GB = 8,192 MiB). The hot-table row "An 8 GB card at 5090 occupancy" (line 73) counts 8,160 warps; a real 8 GB card has 20 to 24 SMs, so its scratch is about a tenth of that row. Resident warps below are SMs x 48 (NVIDIA Ampere and later), SM counts from memory, approximate; Apple uses the 2,048 warps the Metal harness launches (hot-table.md 66).

2. Table 1: non-dataset working set per tier (MiB)

Worst = scratch 128 KiB, cache resident. Columns g / y4 / y12 = genesis, year 4, year 12 (the cache doublings). Freed = era-layout's reading, constant over the years.

Tier	Card assumed (SMs, approximate)	Warps	Scratch 128 KiB	Scratch 32 KiB	Cache resident, 128 KiB: g / y4 / y12	Cache resident, 32 KiB: g / y4 / y12	Cache freed: 128 / 32 KiB
4 GB	GTX 1650 (14 SMs x 32 warps, Turing)	448	56	14	536 / 792 / 1,304	494 / 750 / 1,262	280 / 238
8 GB	RTX 3050 (20)	960	120	30	600 / 856 / 1,368	510 / 766 / 1,278	344 / 254
12 GB	RTX 3060 (28)	1,344	168	42	648 / 904 / 1,416	522 / 778 / 1,290	392 / 266
16 GB	RTX 5060 Ti (36)	1,728	216	54	696 / 952 / 1,464	534 / 790 / 1,302	440 / 278
24 GB	RTX 4090 (128)	6,144	768	192	1,248 / 1,504 / 2,016	672 / 928 / 1,440	992 / 416
32 GB	RTX 5090 (170)	8,160	1,020	255	1,500 / 1,756 / 2,268	735 / 991 / 1,503	1,244 / 479
Apple 8 to 64 GB	M-series, harness launch count	2,048	256	64	736 / 992 / 1,504	544 / 800 / 1,312	480 / 288

Every row = scratch + 96 (hot table) + 128 (buffers) + cache (256 / 512 / 1,024 when resident). The freed reading still peaks at dataset + cache during the daily build, but that peak is smaller than the resident total whenever hashing pauses for the build, so the freed column is the steady-state set.

3. Table 2: dataset room and the year the dataset outgrows it

Room = usable memory (75%, Apple 50%) minus Table 1. Worst = 128 KiB scratch, cache resident (room shrinks at years 4, 12, 28, 60). Best = 32 KiB scratch, cache freed. Option (a): the year 2,048 + 512 x y exceeds the room. Option (b): the first step the room cannot hold; the card mines up to that day.

Tier	Usable MiB (share)	Room at genesis, worst / best	(a) ends, years, worst / best	(b) ends, year, worst / best
4 GB	3,072 (75%)	2,536 / 2,834	1.0 / 1.5	4 / 4
8 GB	6,144 (75%)	5,544 / 5,890	6.3 / 7.5	12 / 12
12 GB	9,216 (75%)	8,568 / 8,950	12.0 / 13.5	12 / 28
16 GB	12,288 (75%)	11,592 / 12,010	17.1 / 19.5	28 / 28
24 GB	18,432 (75%)	17,184 / 18,016	28.0 / 31.2	28 / 60
32 GB	24,576 (75%)	23,076 / 24,097	37.6 / 43.1	60 / 60
Apple 8 GB	4,096 (50%)	3,360 / 3,808	2.6 / 3.4	4 / 4
Apple 16 GB	8,192 (50%)	7,456 / 7,904	10.1 / 11.4	12 / 12
Apple 32 GB	16,384 (50%)	15,648 / 16,096	25.1 / 27.4	28 / 28
Apple 64 GB	32,768 (50%)	32,032 / 32,480	55.1 / 59.4	60 / 60

What the table says per tier:

Tier	Reading
4 GB	Mines at genesis with 488 to 786 MiB spare. Under (a) it is out within 1 to 1.5 years. Under (b) it lasts to the year-4 step, as the spec's own remark says (line 442)
8 GB	6 to 7.5 years under (a). 12 years under (b): "more than a decade" is true only under (b), and only just
12 GB	The year-12 cache doubling (1 GiB resident) is what ends it, under both options, if the cache stays resident. With the cache freed it reaches year 28 under (b). This tier's lifetime is decided by the cache residency question, not by the dataset
16 GB	17 to 19.5 years under (a), year 28 under (b)
24 GB	Under the resident reading the year-28 cache doubling (2 GiB) ends it the same day under both options. Freed: 31 years or year 60
32 GB	38 to 43 years under (a), year 60 under (b). Not a constraint for any plan
Apple 8 GB	2.6 to 3.4 years under (a), year 4 under (b). The base 8 GB Apple laptop is a short-lived miner
Apple 16 GB	10 to 11.4 years under (a), year 12 under (b): the same shape as an 8 GB card
Apple 32 / 64 GB	25 years and 55 years or more. No constraint

Proving is a separate budget (the 15.6 GB peak the 12 GB mine-and-prove question came from); this file covers mining only.

4. Table 3: the public sentences against the numbers

Where	Sentence now	What the tables give	Proposed sentence (the project lead decides the wording)
site/index.html 443	Memory: "2 GB, fixed" (RandomX) / "2 GB, growing" (Igneum)	2 GiB at genesis, plus 0.5 GiB a year on average under either option	"2 GB, growing 0.5 GB a year". The row is right; the rate is the useful addition
site/index.html 461	"Any 4 GB card, approximate."	True at genesis (2,584 to 2,834 MiB of a 3,072 MiB budget). Ends at 1 to 1.5 years under (a), year 4 under (b)	"Any 4 GB card at launch, 8 GB for the long run, approximate."
site/litepaper.html 560	"a 4 GB card mines for about four years and an 8 GB card for more than a decade, approximate."	4 GB: 1 to 1.5 years (a) or 4 years (b). 8 GB: 6.3 to 7.5 years (a) or 12 years (b). Both numbers hold only under option (b)	If gate 1 picks (b): "a 4 GB card mines until the first dataset step at year 4, an 8 GB card until the second at year 12 and a 16 GB card until year 28, approximate." If (a): "a 4 GB card mines for about a year, an 8 GB card for about seven and a 16 GB card for about seventeen, approximate."
site/litepaper.html 560	"12 GB or more proves full shards."	Not a lifetime claim; left as is. For mining, 12 GB lasts 12 years with the cache resident, year 28 with it freed under (b)	No change from this file
docs/evidence.md	No row on card lifetime	The litepaper sentence is a public claim with no row	Add a row, label "designed", sources: spec 1.13.3 and this file; status moves to "tested" once a 4 GB and an 8 GB card run the genesis working set under the cap

5. Reading

• The two index-mapping options end on the same day where a cache doubling takes the last of the room. With the cache resident that is the 12 GB tier at year 12 and the 24 GB tier at year 28 (Table 2, worst column). Under option (b) every tier ends on a step day by construction, so a tier ends on the same day under both options exactly when option (a) also ends it on a doubling day.
• Everywhere else option (b) is kinder: 4 GB gains about 2.5 years, 8 GB about 5, 16 GB about 10. The site and litepaper numbers are option (b) numbers. If gate 1 picks (a), both public sentences are wrong today by 2.5 to 5 years.
• The cache residency disagreement (hot-table.md 70 against era-layout.md 93) decides the 12 GB tier's lifetime (12 against 28 years) and nothing else. It should be settled at gate 1 beside the mapping choice.
• The 75% rule is my generalisation of "under 6 GB on an 8 GB card"; at 4 GB it leaves 1 GB for the driver and the display, which a headless rig would not need. A 4 GB card on a bare Linux rig might hold out to year 2 under (a). Not measured.