canoli wrote:Sh-- thanks for pointing that out. No way I'm wasting money on a PCIe x1 card. The Koutec (whoever they are) doesn't specify and the reviews aren't great all in all. Lot of compatibility issues it seems.
You can tell it is x1 by the width of the PCIe connector in the product photo. A small connector like that is an indication of an x1 interface. A larger connector (x4, x8, x16) means that the card might
be capable of running at the rate implied by the connector size, but you're still subject to any electrical limitations of the chip(s) involved (as we've been discussing).
canoli wrote:I took it for granted these cards would all be PCIe x16 or x8 by now. Do I need to spend $$ and buy a real RAID card to get the top PCIe speeds?
If you want to load up all the ports and run all the drives at full speed simultaneously, then generally yes. You're basically getting into server-class hardware.
Be aware that many of these cheap PCIe x4 cards actually have multiple PCIe x1 SATA controllers connected via a bridge chip and therefore are capped at a maximum PCIe x1 bandwidth on any individual SATA port.
It can be hard to work this out from the manufacturer specifications, but if you look at the Startech details here
you can see that it lists the controller as the Marvell 88SE9128 with bridge chip PEX8604. If you Google the controller name, you can find a datasheet here
which shows that the chipset PCIe link is just x1 width.
Yup. There are two of those Marvell chips on the card though, so maybe you can achieve effective PCIe x2 bandwidth... provided you're talking to a pair of drives that aren't connected to the same Marvell chip?
canoli wrote:Were you saying the PEX8604 - what you termed the "bridge chip" - is that the concern? I can't find anything on that chip unfortunately.
(Not that it really matters, you're going to be limited by the x1 interfaces to the Marvell chips anyway...)
@canoli, if you're comfortable buying used this is probably your best bet for getting server-class hardware on the cheap.
If you don't want to do that (and have the PCIe slots available), your best bet from a bang-for-the-buck perspective may actually be to buy a pair of 2-port x1 cards.