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 Post subject: freeing up PCI express lanes disabling bios
PostPosted: Fri Mar 16, 2018 5:01 pm 
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Joined: Sun Jan 25, 2004 2:01 am
Posts: 1243
I just recently purchased a ASUS p5k to replace both my msi 975x and gigabyte p35 dsr3

both died.

P5k works.

one issue i discovered is

the intel p35 has 16 lanes directly connected to the north bridge

the Intel I/O Controller Hub 9 supports 6 lanes

2 lanes are used, 1 lane for gigabyte ethernet port and 1 lane for jmicro sata raid/pata ports which i am not using

on newegg several owners said complained that when there is a second graphics card in the 16x slot, they get 4x speed and the pci 1x doesn't work. some said they have raid

i use the pci e 1x for a dlink 556 wireless n card, though in retrospect i guess i should have got a pci card. asus p5k has 3

i'd like to install a m2 adapter 4x and use clover efi to boot, possibly and continue to use my wireless n card on the 1x slot

if i disable via bios either or both gigabyte ethernet and/or sata raid/pata will i be able to free up pci lanes for the remaining 1x slot or it doesn't work that way

i would buy this m2 at microcenter vantec in the event i can't get clover bootloader to work

asus p5k p35 is sata 2 not sata 3


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 Post subject: Re: freeing up PCI express lanes disabling bios
PostPosted: Sat Mar 17, 2018 2:44 am 
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Joined: Fri Aug 05, 2005 3:29 am
Posts: 1637
Location: UK
PCI-Express lane management is still necessary even with the latest generation of Asus (and other makes) Intel Z370 boards. On your particular board it was designed to be AMD Crossfire compatible. So if both the PCI-E 16x slots were occupied with AMD graphic cards it would auto-select 8X speed for each card. Because this was based on auto-sensing there is the potential for it not to work as expected. For anything other than graphics cards the auto-sensing would set the slot speed to 4X. And as far as I remember there is nothing in the BIOS to over-ride that. And of course this is the earlier PCI-Express 1.0/1.1 standard so a 4X slot would be equivalent to approximately 1X on a PCI-E 3.0 board.

If you really want to try an NVME adapter then it should work with the help of Cloverleaf EFI. However what speed the NVME drive would run it at is problematic. It is going to be hardware limited because of the reasons already touched on. My opinion is that it will be around 20 to 25% of its speed on 4X PCI-Express 3.0 at best. Probably around the same speed as a SSD drive attached to one of your SATA II ports. Maybe you should try it anyway and see what results you get.


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 Post subject: Re: freeing up PCI express lanes disabling bios
PostPosted: Sat Mar 17, 2018 8:17 am 
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Joined: Sun Jan 25, 2004 2:01 am
Posts: 1243
lodestar wrote:
PCI-Express lane management is still necessary even with the latest generation of Asus (and other makes) Intel Z370 boards. On your particular board it was designed to be AMD Crossfire compatible. So if both the PCI-E 16x slots were occupied with AMD graphic cards it would auto-select 8X speed for each card. Because this was based on auto-sensing there is the potential for it not to work as expected. For anything other than graphics cards the auto-sensing would set the slot speed to 4X. And as far as I remember there is nothing in the BIOS to over-ride that. And of course this is the earlier PCI-Express 1.0/1.1 standard so a 4X slot would be equivalent to approximately 1X on a PCI-E 3.0 board.

If you really want to try an NVME adapter then it should work with the help of Cloverleaf EFI. However what speed the NVME drive would run it at is problematic. It is going to be hardware limited because of the reasons already touched on. My opinion is that it will be around 20 to 25% of its speed on 4X PCI-Express 3.0 at best. Probably around the same speed as a SSD drive attached to one of your SATA II ports. Maybe you should try it anyway and see what results you get.


+1

I wish this forum lets me like and up vote like other forums.

I take it then bios disabling the gigabyte ethernet port and sata raid/pata jmicro should free up the 1x pci so i can continue using wireless along with 4x. is that correct? i can continue using wirelss n in pcie 1x provided i also disable the onboard ethernet port and sata raid/pata jmicro which frees up 2 pcie 1x lanes.

the nvme will go to the 4x pcie and hopefully 4x pcie 1.0

i had over wiki it says

SATA revision 2.0 (3 Gbit/s, 300 MB/s, Serial ATA-300)

1.0 2003 8b/10b 2.5 GT/s 250 MB/s 0.50 GB/s 1.0 GB/s 2.0 GB/s 4.0 GB/s

https://en.wikipedia.org/wiki/Serial_AT ... al_ATA-600)
https://en.wikipedia.org/wiki/PCI_Express


that sata 2 is 300mb/s
pci 4x 1.1 is 1000 mb/s or 3 times the bandwidth
plus lower latency


do i have to configure the bios for the second 16x slot?

it seems the bios expects that slot to be occupied by a second graphics card and not a general purpose card like nvme card

yeah i head over to youtube

the vast majority of clover efi booting is for mac os sierra

but there are vids like this

https://www.youtube.com/watch?v=PxfkwgxLL2c&t=1044s

over 1-2 hours in length. :o

that explains i need certain drivers and how to install clover and boot windows 10 which :shock:

apparently i have to partition the ssd, create a MBR, install clover on a MBR, second partition is GUID
hunt down efi drivers and nvme drivers, and install windows on the second partition.

clover boots first on the mbr then creates a UEFI that can then load windows, kinda like a virtual machine.

most of the instructions are for booting mac os sierra though

some ssd are sold with this pcie nvme adapter at the included cost including one by kingston, which is lower price or costs same as samsung evo 960 at newegg and amazon.
of course if it doesn't work i want to return it and so i may be stuck with microcenter
thanks


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 Post subject: Re: freeing up PCI express lanes disabling bios
PostPosted: Sat Mar 17, 2018 8:32 am 
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Joined: Sun Jan 25, 2004 2:01 am
Posts: 1243
pci e lane management reminds me of IRQ of yore.

back in the day i had to figure out IRQ's

i kinda forgot just vague memories of dip switches jumpers and autoexec.bat and config.sys files


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