HP Compaq DX 7500 (Pegatron 2A84H board) - what PCI-E version is implemented on 1x slots?

[mwlodarc]

Hello,

I cannot find any information about PCI-E version iin my desktop hp DX 7500.

I recently added ASM1061 PCI-E (1x) card to support Sata 3 and use my SSD drive more efficiently (since onboard DX 7500 supports only Sata 2), but was disappointed by the performance on the add-on PCI-E card.

I suppose the limitation can be PCI-E 1.0 version - which is 250MB/s (while PCI-E 2.0 is 500MB/s).

Co you know if all three PCI-E slots are 1.0?

The only information I found is that table:

http://www.findlaptopdriver.com/pegatron-corporation-2a84h-motherboard-rev-1-03-specs/

According to this, my PCI-E 16x is 2.0, but there is no word about version of PCI-E 1x ports...

Best regards,

Marcin

[erico]

I have never heard or read any discussion of a specification for PCIe x1 except that its maximum bandwudth is 250 MB/s.

It is x1, not 1x.

Devices that use the PCIe x1 slot are limited to a theoretical data transfer bandwidth of 250 MB/s.

The official PCI / PCIe specification white papers are at the following URL for your reference.

http://pcisig.com/specifications/pciexpress/resources/PCI_Express_White_Paper.pdf?field_technology_v...

[mwlodarc]

According to:
https://en.m.wikipedia.org/wiki/PCI_Express
there are different versions. 1.x is indeed limited to 250MB/s. 2.0 however is limited to 500MB/s.
I read that my PCI-E x16 port is 2.0. I wonder what version are my x1 ports.

[erico]

I can ask the HP Engineers for you. They designed the specifications required for your PC's motherboard. It may take a few days for a response, so please be patient.

One thing to note is the regardless of the PCIe 1 slot version implementation, an overall limiting factor will be the bandwidth of the chipset busses on the motherboard. That is why installing a PCIe x1 card may not produce the advertised bandwidth.

[mwlodarc]

That would be great - thanks in advance!

I don't know where is the bottleneck now. Is it my HP DX 7500 PCI-E rev 1.x and thus 250MB/s or it is Asmedia ASM1061 card that doesn't perform ...

[Big_Dave]

Hi,

Try SIV. 

@erico  FYI

[erico]

@Big_Dave

I had forgotten about SIV.  I had to play with it a bit to see that my ASUS R.O.G Crosshair V Formula Z has V2 PCIe x1 slots.

@mwlodarc

Download the appropriate SIV version (match your OS architecture) to see what your motherboard has. Check out the followinbg image which shows my desktop motherboard.

[mwlodarc]

Thanks! Ok, I see that my PCI-E x1 is 2.0 because it can handle 5 GB/s, but somehow (now it is really weird why) my Asmedia card negotiated only 2.5 GB/s - do you have any idea how the negotiation works like is there any option to force 5 GB/s?

I have another issue that I don't understand:

At the current settings my SSD drive works better when connected to onboard SATA II port compared to Asmedia. This is because of the constraints: 3 GB/s for SATA II vs 2.5 GB/s for "negotiated" Asmedia.

Now, if I have my system SSD drive connected to the HP mainboard and any disk or optical drive connected to Asmedia PCI-E, I cannot boot my system 😞 It is really frustrating. When I enter BIOS (which is extremely simplified btw) and go to Hard Disk group I only see disks connected to Asmedia card, I don't even (at BIOS level) see any disk connected to onboard port. When there is nothing connected to Asmedia card, everything works properly (and also in BIOS I see disks connected to onboard sata ports). It looks like the Asmedia cards somehow (?) gets priority when booting system and the system ignores onboard ports.

The optimal solution in my case could be to have Asmedia working at 5GB/s, so my system disk boots from Asmedia and everything else works correctly.

[mwlodarc]

I only see (btw: thanks for showing me SIV!) that my Asmedia uses the same IRQ that my nvidia 1030 for audio purposes. Maybe switching PCI-E ports would help?