Post by DanThanks Paul. I was worried that either power supplies were not
compatible with newer motherboards.
Maybe we start backwards a bit. With something we don't need.
The power connector for the RTX4090 is here, and not well documented.
This connector might well be at its third revision, having recently
been released again with slight mods to the sense pins. This is well out
of my budget range or interest, because this connector is still melting
on people, even when the connector has been properly seated. This
might be referred to as ATX 3.0 , versus the kind of ATX 2.2 which
is more common (with PCI express 2x3 or 2x4 power connectors covered
by a 2x3+1x2 split connector). Gamers have to do their own research
on this particular item. It's beneath contempt to be spending a couple grand
on electronics and it's still not perfected.
https://en.wikipedia.org/wiki/16-pin_12VHPWR_connector
https://www.overclockers.co.uk/blog/12vhpwr-what-is-it-and-why-do-you-need-it/
The specs for ATX used to be on formfactors.org (an intel-owned site),
but Intel has messed this about. This would cover a good deal about
what a builder needs to know. Modern supplies use double-conversion
(12VDC feeds a 3.3V/5V converter board) and the specs on voltage uncertainty
achieved are tighter than they used to be. There is less of a cross-loading
effect with double conversion, and heavily loading one rail, does not
cause another rail to "deviate" like it used to. The better performance
of the ATX supply comes in handy, when you connect a "picky" 22TB hard drive.
http://www.formfactors.org/developer/specs/ATX12V_PSDG_2_2_public_br2.pdf
( https://web.archive.org/web/20070112183223if_/http://www.formfactors.org:80/developer/specs/ATX12V_PSDG_2_2_public_br2.pdf )
*******
The author of this, is not up to ATX 3.0 .
However, there are pictures of connectors here, both old and new. The six pin Aux
for example, that's not really all that common on motherboards any more.
http://www.playtool.com/pages/psuconnectors/connectors.html
But many of the other things you should know about connectors, are present.
*******
You will plug in a 24 pin main connector.
Now, ATX started with a 20 pin connector. At a later date, they needed a
bit more 12V power for PCI Express video slots and the like. The main ATX
connector became 24 pin at that point. Of the extra four wires, one of
the wires was yellow, and that's where the extra 12V comes from.
A lot of supplies are 20+4, and you carefully join both hunks and plug the thing in
as a 24 pin connection. One of the pins on there is "PS_ON#" and grounding
that pin, turns on the supply. The motherboard normally drives PS_ON# low
to actuate it. In the EVGA box, you may find a "plastic thing" with "two shiny
pins" and that is a PS_ON# activator for testing the supply without a
motherboard connected. I have a switch and a couple of pins here I use,
for the same PSU test purposes.
The next thing to connect, is the ATX12V. It started as a 2x2 connector, with
2 yellow and 2 black wires. The yellow wires carry up to 6 amps of current.
Two yellow wires is 12 amps. Times 12V is 144 watts. This is sufficient to
cover a turbo operation of a 65W processor.
However, the motherboard will have a 2x4 connector on it. Plugging in
two 2x2 connectors would give room for 288 watts to flow. The connectors,
the nylon shells have different shapes, and the two of them are not
the same. They are pressed together, to make the 2x4 connector. This would
be how you're going to connect your system. Even though the wires have
sufficient gauge for 288 watts, when the computer is idle, the wires will be
cool, and only a few amps will flow through the four (paralleled) yellow wires.
When people make a mistake during a build, it's forgetting to plug that 2x2 or 2x4
assembly in. The motherboard is most likely to have a 2x4 and your power supply
will also have the cable to do 2x4.
That is really all yours needs at the moment.
*******
If you had a video card, it would take:
1) Low end - no additional connectors (~60W from "slot connector")
2) One 2x3 or one 2x4 (75W or 150W connector)
3) A 2x3 plus a 2x4 (225W total)
...
4) The 600W connector the RTX4090 uses (which could have been done with multiple 2x4 if they'd wanted)
The PCIe connector is a 2x4, split into a 2x3 and a 2x1 so that the connector
can be made into a 2x3 or made into a 2x4. Just because a supply has a raft
of PCIe connectors, you still have to do the arithmetic to determine if
there are enough watts for the entire load.
SATA drives have a 15 pin power connector. Pins are rated at 1 ampere each.
You could draw 12V @ 3A for example, sufficient to spin up any HDD today.
Small hard drives draw larger startup currents than large capacity drives.
This is to "make the small (boot) drive ready faster". The power footprint
in any case, seldom exceeds 12V @ 2A today, which is why the SATA connector
is fine. It might take 10-15 seconds for a 22TB hard drive to "become ready".
Older drives used the 1x4 Molex, which like other Molex supports 6A to 10A ampacity,
depending on the gauge of wire stuffed into the pin, and, how many nearest
neighbours are heating one another in the connector. If you need to make
a "distribution tree", using Molex to SATA adapter, better stays within
the current flow limits of the connector. Using a Y connector with SATA 15 pin
on either end, that's not really a good idea (it's not a good idea to chain
a lot of SATA to SATA to SATA adapters together, the pins are too weak for this).
That should be enough to get you started. With your proposed build
and your inserted NVMe SSD drive, really, only two connectors will be used,
which is the 24 pin main and the 2x4 with the 288W room for the CPU.
Some motherboards have even more than the 2x4 ATX12V assembly, as some processors
could be taking 400W in turbo for a short time. Just hook up your 2x4
and you'll be fine - you don't have a $1000 motherboard with 20 phase power,
so the motherboard cannot convert 400W and does not need a multitude
of 2x4 connectors for ATX12V as a result.
*******
Some day, computers may be run off 12V only, but I don't think we are there
yet. Any time they mess about with "where something is done", the price
seems to go up. Which is why we like them to leave well enough alone.
*******
You have not selected a backup drive yet.
A WD Black 1TB 3.5" drive, that's a conventional drive with holes in
it which mate with trays in modern computers. This is an "air breather"
hard drive -- a hepafilter filter hole equalizes HDA air pressure with
external atmospheric. Drives continue to breathe air, up to 6TB guaranteed,
and maybe occasionally someone makes an 8TB air breather. I generally
don't go over 6TB if I want the reliability of an air breather.
Drives larger than that, are filled with Helium gas, sealed, and have
a gas cover and a mechanical protection cover (*welded down*). Helium
drives have the mounting holes in a different place, for the 3.5" ones.
Helium drives also have 3.3V spin control - a computer SATA connector
with *five* wires, doesn't work with the Helium drive. You want a SATA
connector with *four* wires, as the four wire configuration does not
send 3.3V to the drive... and the drive is then allowed to spin up.
You might see an issue, if placing an 18TB to 22TB expensive hard
drive in your new PC for backups. I don't really think that's in
your budget, and this is just a warning for the future.
Other backup drive options exist. But I prefer the 3.5" drives as
it's been a long time since I've had a failure. There are portable 2.5"
drives for example. Those go up to 5TB max and 15 mm high (the drive
would not fit in a laptop because of the height, even if the
interface connector was changed to the correct type).
You could do backups to the cloud, and for your parents data purpose
(protecting just the data, not the OS installation), any number
of cheap things can be used for that much of a backup scheme.
Microsoft has their cloud drive scheme, for which some small
number of terabytes are free.
There are a lot of practical issues, with getting "parents" to make "backups".
It's not a topic where "just spending money" leads to good practice,
unfortunately. I don't think the scheme I made for "parents",
ever got used for backups. You have been warned :-) Only
techie types make backups :-)
Paul
