What are the most expandable, backwards compatible, modern computers?

[cdev]

When I bought my current decktop, now almost a decade old, one of the selling points of the motherboard was their alleged use of long life components, also the MB had an old style ATA disk connection and a single old style PCI slot (non-PCI-e, along with a normal number of PCI-e slots.. I guess its target market was cheapskates like me.. Anyway, its served me well and continues to do so, mostly. I may upgrade it fairly soon, though. What are other motherboards that share this design philosophy, where they make it possible to use both modern tech and "trailing edge" tech from yesteryear at the same time?

I dont like to be forced to buy new hardware.

[Whales]

Ditto for my current motherboard (2011-era).  I like having the old PCI slot.  On reflection however: the most I've really used it for are TV tuner cards and diagnostic cards.  I can't think of much else.

There are bridging chipsets used to make adaptors to provide PCI or ISA over PCIE.  Never tried them but I presume they're reliably and well supported given that some PCIE cards actually contain these chips on them. 

You can buy some specialist "industrial" motherboards that come with PCI and/or ISA slots on them.  They cost a lot more and are rarer.  I assume they just put the same PCIE-to-PCI/ISA bridge chipsets on the motherboards instead?  I wonder if southbridges still expose ISA or if it's an internal-only bus now? (modern chipsets still report ISA temperature probes and other stuff to the OS).

PCIE is fully backwards compatible, so anything that currently works in your PCIE slots will continue to.

I don't think any motherboards have gotten rid of SATA yet, which is good.  M.2 is getting more popular but all of the disks I have are SATA and I want to keep using those.

Some motherboards use the new ATX12V specification for power, I'm of the opinion of avoiding those.  You need a different style of power supply (or an adaptor) and if any of the switchers on the motherboard fail then the whole motherboard is junk.  I've been known to mysteriously kill motherboard parts with my magic touch

Avoid OEM motherboards (those that come in pre-built computers), those tend to be non-standard in weird and wacky ways.  An off the shelf motherboard is always the better option.

In terms of CPU sockets: I don't know what to recommend at the moment.  You'll have to look at both Intel & AMD's offerings to see which looks like it's going to be better in the long term.  I'm using one of the "newest" processors that my motherboard supports, released well after the motherboard itself, because I had a few years of good CPU support.  It wasn't high end but it's now pretty cheap.

I am now at a point where I'm interested in upgrading my CPU, but it's an expensive proposition for me.  Around $200 for a new CPU, $125 for a new motherboard and $100 for new DDR4 RAM (I only have DDR3).  The rest of my parts should continue to work, however

[free_electron]

if it ain't got a good old isa card , it's not backward compatible. some will even say if it doesn;t use gpib to connect external harddisks or can run rocky mountain basic programs it's not backward compatible. real greybears will tell you if it can;t run OS260 or emulate an IBM360 instruction set it ain;t backwards compatbile. The real crufty ones will reach for their stack of punch cards and 5 bit paper tape.

what's the point ? how long do you want to drag along all that old stuff ? I'm using 7 year old Z-book machines. has everything you could wish for and runs even the heaviest programs. Plenty of them on ebay. Can drive 3 external screens and has 4 storage bays. ( 2 x 2.5 inch drive bays , a cdrom bay and an eSata module bay. slap in a terabyte of emmc , two 4 terabyte laptop drives , 32 gig of ram and a dvdrom. hook it to its dock station ( where you can slap in another desktop harddisk and a cdrom drive ) and off you go. it has usb 3 , displayport , thnuderbolt and all you could possibly want.
Get one with a Quadro K4100 or K5100
if you look around you can find Gen II machines for like 500$

[50ShadesOfDirt]

If building a modern desktop (from scratch), I'd find the best combination of mobo, cpu, and ram that is in the price range you need. For me, the sweet spot is always a gen or 2 back from whatever is current; as long as it has SATA, USB3 or later, etc., I can hook up anything to it. I escape the temporary "premium" price in this way.

If you've got some really old stuff that you have to drag along, I wouldn't cripple the new mobo with old stuff. See if any of the "industrial" designs still have ISA or whatever you need, in a small-form industrial package. I'm amazed at how many of these are still supporting ISA, older Windows OS's, and so on. Apparently, industry still runs things on DOS ...

Hook both up over the network, but by separating in this way, old stuff doesn't cripple new stuff. You should be able to "remote in" to the old stuff from new systems, and control hardware and software. A VGA/keyboard/mouse switch, and one monitor handles both, if remoting in isn't a good fit.

Hope this helps ...

[David Hess]

Do you have any PCI cards that you actually want to use?  My previous system, built around 2011, lasted until last year when I decided that I needed more RAM than it would economically support.  Its replacement lacks PCI slots, but there was nothing I could not find in a PCIe card if necessary now and I made sure to get a motherboard with plenty of PCIe slots.

New motherboards with PCI slots through a bridge chip are available if you need that level of backwards compatibility.

[themadhippy]

only backward compatibility i look for is a proper serial port,yea theirs multiple usb to serial  adapters available,but ive yet to find one that just works regardless of whats hanging off the end.

[m k]

From the beginning I've practically always had more than one machine, for professional support purposes I've also always had at least one for old tech.
Nowadays extra need is practically only some spinning disk rescue situations, also excluding all part swaps.

Based on those experimentences I'd say that today on purpose hardware is sort of exceeding on purpose software.
Linux has also dropped x86 and Microsoft much more so my experimentence seems to be valid.

But even that Linux is officially dropping some support it doesn't mean that support is not possible.

So as long as Linux is around and hardware has a fast enough connection possibility it can be expanded and can be made backwards compatible.
One exception, mandatory IoT DRM hardware.

E,
nuances.

[DiTBho]

The problem is that most PCI and PCIe cards are for x86 and don't work correctly on other architectures. Why? Shouldn't PCI and PCIe be designed to be "architecture independent"?

Well, in theory, yes, but ... in practice, there are a lot of things you find around x86 that you don't find elsewhere.

[Halcyon]

Depends what you mean by "backwards compatible" and what your requirements are.

It's trivial to add legacy support for things like RS-232 serial, IEEE 1394 (FireWire), Parallel ports and IDE hard disk interfaces to very modern machines. StarTech and other brands make PCIe cards for these types of older interfaces.

[Bicurico]

My PC is quite old by now. It runs on an Intel Core i7 of the fourth generation

But as the OP I have this requirement to keep using my cards. These include special satellite receiver card on PCI and capture card, Dektec modulator card, etc. for PCIe slots.

The PCI slot could be sacrificed, as there are PCIe versions of the satellite card (needs to be compatible with CrazyScan).

But the real struggle is that modern motherboards have only 1-2 free PCIe slots, apart from the one dedicated to the graphics cards.

I would like to have a motherboard that has at least 4 free PCIe slots, apart from the graphics card.

[coromonadalix]

Asus Z87-WS  has 4 pcie slots ... and 2 pci-e 1x

Asus P9X79-E WS  7 pci-e slots



For the higher end boards

you have some x99 based chipset and x299 chipsets,  they can go up to 7 slots .... but $$$

[themadhippy]

But the real struggle is that modern motherboards have only 1-2 free PCIe slots, apart from the one dedicated to the graphics cards.

older boards wernt much better off,yea they may have offered 6 expansion  slots,but nothing was built into the motherboard ,so if you wanted disc drives,output for a display,sound and networking theirs  4 of your slots gone.

[Bicurico]

Asus Z87-WS  has 4 pcie slots ... and 2 pci-e 1x

Asus P9X79-E WS  7 pci-e slots



For the higher end boards

you have some x99 based chipset and x299 chipsets,  they can go up to 7 slots .... but $$$

Thanks! Didn't know these two boards.

Since I have not built any PC in the last 10 years, I have not followed up the PCIe specification too closely.

The specs say "Expansion Slots - 7 x PCIe 3.0/2.0 x16 (single x16 or dual x16/x16 or triple x16/x16/x16 or quad x16/x16/x16/x16 or seven x16/x8/x8/x8/x16/x8/x8, black+blue) *"

What does that mean?

I understand that the x16 mean the bandwidth. So one PCIe lane can have an x16 PCIe card or two x8 cards?

Can PCIe cards automatically switch from x16 to x8 mode?

Am I right to assume that only graphics cards will use x16, while almost all other cards will be happy with x8, x4, x2 or even x1?

Why are some slots in bue and other slots in black? Will the black slot share the bandwidth with the blue one?

Why doesn't this make sense in my head: "x16/x8/x8/x8/x16/x8/x8"? This does not add up in the x16/x8+x8 logic...

[SiliconWizard]

Am I right to assume that only graphics cards will use x16, while almost all other cards will be happy with x8, x4, x2 or even x1?

Current NVMe SSDs will usually use 16x PCIe. At least the good ones.

[NiHaoMike]

But as the OP I have this requirement to keep using my cards. These include special satellite receiver card on PCI and capture card, Dektec modulator card, etc. for PCIe slots.

The PCI slot could be sacrificed, as there are PCIe versions of the satellite card (needs to be compatible with CrazyScan).

But the real struggle is that modern motherboards have only 1-2 free PCIe slots, apart from the one dedicated to the graphics cards.

I would like to have a motherboard that has at least 4 free PCIe slots, apart from the graphics card.

There are adapters that take a PCI card and adapt it to PCIe. Not sure on compatibility.

You can also look at "1 to 4" PCIe splitters that were developed for crypto mining.

[Whales]

Am I right to assume that only graphics cards will use x16, while almost all other cards will be happy with x8, x4, x2 or even x1?

Why are some slots in bue and other slots in black? Will the black slot share the bandwidth with the blue one?

Why doesn't this make sense in my head: "x16/x8/x8/x8/x16/x8/x8"? This does not add up in the x16/x8+x8 logic...

I'm not 100% sure, but from what I understand:

 * PCIE slot colour: check the motherboard manual.  Everyone makes it mean a different thing (or nothing at all). 
 * Lane allocations: check the motherboard manual.  I believe this is handled in BIOS.  Some will let you manually allocate.
 * Numbers not adding up: be wary of PCIE switches (a bit like ethernet switches) that some motherboards use, and also be wary of lanes coming directly from the CPU versus the chipset.  These are common and not necessarily bad at all, but are often misrepresented by manufacturers.
 * Most (all?) PCIE cards will accept any amount of lanes?  Something about PCIE being a switched packetised standard, so everything gets worked out by the PCIE bus interface silicon?

[David Hess]

only backward compatibility i look for is a proper serial port,yea theirs multiple usb to serial  adapters available,but ive yet to find one that just works regardless of whats hanging off the end.

That is my experience with USB to serial converters; they only work properly in the least demanding applications, and often not even then.

My 2011 system was suppose to have a built in serial port, but the level translators were missing.

I have gotten by with a PCI serial card, and if I need one now, I will get a PCIe serial card, although I think my 2021 system does have a working serial port.

[ejeffrey]

The specs say "Expansion Slots - 7 x PCIe 3.0/2.0 x16 (single x16 or dual x16/x16 or triple x16/x16/x16 or quad x16/x16/x16/x16 or seven x16/x8/x8/x8/x16/x8/x8, black+blue) *"

What does that mean?

If you use only the four blue slots you get 4 slots with x16 lanes each.  The three black slots are x8 each.  Two of them -- the top and bottom (labeled x8/x0) also share lanes with the 2 blue slots that are labeled (x16/x8).  Therefore if you use all 7 slots, only 2 slots will be x16, all the rest x8.  There are a total of 72 lanes between the 7 slots.

I understand that the x16 mean the bandwidth. So one PCIe lane can have an x16 PCIe card or two x8 cards?

lane = serial data channel.  slot = physical connector for a card.  x16 means 16 lanes for that slot.  PCIe allows the mechanical slot size to be different from the electrical size and negotiate down to use the lanes available.

Can PCIe cards automatically switch from x16 to x8 mode?

Yes.  Even x4 or x`, whatever is available.

Am I right to assume that only graphics cards will use x16, while almost all other cards will be happy with x8, x4, x2 or even x1?

In the consumer space yes.  GPUs are about the only thing that will use 16 lanes.  I'm sure in the datacenter there are high performance networking, storage, FPGA and ML accelerators that use x16, but most that I have used top out at x8. The only other really high performance device most people use is an SSD.  Most consumer SSDs these days are in the M.2 form factor which has 4 lanes.  There are some in the standard PCIe card form factor that are x8.

Why are some slots in bue and other slots in black? Will the black slot share the bandwidth with the blue one?

Color coding is up to the motherboard manufacture, but yes often indicate bandwidth sharing.  Another possibility is showing which slots are connected directly to the CPU and which go through the chipset.  This is common when the CPU supports a faster version of PCIe than the chipset (say PCIe 3.0 vs 2.0).  You basically have to check with the manual to see what it means on any given motherboard.

[David Hess]

I understand that the x16 mean the bandwidth. So one PCIe lane can have an x16 PCIe card or two x8 cards?

Many motherboards with multiple x16 slots use a PCIe bridge to split x16 into dual x8, so that if one slot is used it is configured as x16, but if the other slot or both slots are used, then they are x8.

But the real struggle is that modern motherboards have only 1-2 free PCIe slots, apart from the one dedicated to the graphics cards.

But you can still find new boards at a reasonable price with a split pair of x16/x8 PCIe slots as I described above, plus another x4 slot, and 2 or 3 x1 slots.

[m k]

only backward compatibility i look for is a proper serial port,yea theirs multiple usb to serial  adapters available,but ive yet to find one that just works regardless of whats hanging off the end.

That is my experience with USB to serial converters; they only work properly in the least demanding applications, and often not even then.

My 2011 system was suppose to have a built in serial port, but the level translators were missing.

I have gotten by with a PCI serial card, and if I need one now, I will get a PCIe serial card, although I think my 2021 system does have a working serial port.

Are these new ports including original I/O instructions?

Windows environment had user programs commanding hardware directly.
Linux has been different from the beginning.

[David Hess]

only backward compatibility i look for is a proper serial port,yea theirs multiple usb to serial  adapters available,but ive yet to find one that just works regardless of whats hanging off the end.

That is my experience with USB to serial converters; they only work properly in the least demanding applications, and often not even then.

My 2011 system was suppose to have a built in serial port, but the level translators were missing.

I have gotten by with a PCI serial card, and if I need one now, I will get a PCIe serial card, although I think my 2021 system does have a working serial port.

Are these new ports including original I/O instructions?

Windows environment had user programs commanding hardware directly.
Linux has been different from the beginning.

The ports I mention here are or simulate 8250/16450/16550 equivalent UARTS with register access through the I/O address space.  Whether accessed directly or through the operating system should not matter.

[cdev]

I understand that the x16 mean the bandwidth. So one PCIe lane can have an x16 PCIe card or two x8 cards?

Many motherboards with multiple x16 slots use a PCIe bridge to split x16 into dual x8, so that if one slot is used it is configured as x16, but if the other slot or both slots are used, then they are x8.

But the real struggle is that modern motherboards have only 1-2 free PCIe slots, apart from the one dedicated to the graphics cards.

But you can still find new boards at a reasonable price with a split pair of x16/x8 PCIe slots as I described above, plus another x4 slot, and 2 or 3 x1 slots.

I always max out on mine, fairly quickly. My current computer is also struggling in the USB area, I just have too much USB stuff. Some of the ports are supposed to have extra power, but this has not helped, it seems. I wish there were better ways to debug this. I have a feeling that some of my post annoying and persistent computer problems are rooted in the USB mess.

[Nominal Animal]

My current computer is also struggling in the USB area, I just have too much USB stuff.

If you're like me, you have "too many" USB 2 devices, and no USB-2-to-3 "converting" hubs.  (Essentially, when using USB 2 devices, each root port is limited to 480 Mbit/s throughput, even though the root port is an USB 3 one.  This is because USB 2 and USB 3 use physically different transceivers on each port.)

I've also found that for the USB 1.1 (Full speed, 12 Mbit/s max) stuff, using an USB isolator followed by an isolated wall wart (non-grounded, fully isolated USB supplies) powered USB hub, can make a lot of things more stable.  Especially so for stuff I designed myself and am working on .

I'm very eagerly awaiting cheap high speed isolators, now that both TI (ISOUSB211) and Analog Devices (ADUM4165) have released high-speed capable isolator chips.  A simplified version of the Olimex USB-ISO (for USB low or full speed only, no high speed support), with a downstream USB power input port (so that one can use a known good isolated USB power supply (no ground pin!), ubiquitous here in Europe, as long as one does not fall for the crappiest-of-the-bunch ones) to power the device.

In fact, I've already taken a look at the ADUM4165 and ISOUSB211 data sheets, with the intent of making my own heavy-duty isolators with Mean Well medical power supply (say, RPS-30-5 or RPS-45-5) for the isolated downstream.  I'd love to have multiple separately isolated USB 2 ports (with a ganged cable to my computer), but I don't know enough about (isolated) DC-DC power conversion to work out how to do that with just one (possibly not so well isolated) power supply, without risking all sorts of EMI issues.  All of my designs thus far are based on datasheet application recommendations and TI Webench schematics.  (With a microcontroller on the host side of one of the ports, for both monitoring the voltage and power use, but also for disconnecting both the power and the isolated port as needed.  I'm especially interested in how "spiky" the current draw of a specific USB device is, at the sub-millisecond scale.  It would be a very useful SBC test bench, especially if it had isolated, controlled and monitored 5V/9V/12V available for powering the target SBC.)

[David Hess]

I always max out on mine, fairly quickly. My current computer is also struggling in the USB area, I just have too much USB stuff. Some of the ports are supposed to have extra power, but this has not helped, it seems. I wish there were better ways to debug this. I have a feeling that some of my post annoying and persistent computer problems are rooted in the USB mess.

I have two monitors which each have 4 x USB 3.0 ports, and a USB 3.0 hub which allows me to turn on/off each port.  My keyboard and mouse plug directly into the computer.

[Doctorandus_P]

Most MoBo's still have a serial port (or maybe two?) even though it's probably not on the back side. It's often just a 0.1" header tugged away in some corner, and maybe the signals are only TTL without line drivers. But it's not a selling point for a long time so shops don't advertise it. You have to check the booklet of the MoBo you're interested in for this.

[David Hess]

Most MoBo's still have a serial port (or maybe two?) even though it's probably not on the back side. It's often just a 0.1" header tugged away in some corner, and maybe the signals are only TTL without line drivers. But it's not a selling point for a long time so shops don't advertise it. You have to check the booklet of the MoBo you're interested in for this.

The problem with mine was that the serial port UART was built into the chipset, and the board was laid out with the header for RS-232, but the external level translator and header were left out despite the specifications and documentation indicating a serial port.  So I installed a PCI serial/parallel board and all was well.