netkas.org

2.5 GT/S, is it really an issue?

Many radeionhd 48×0 and geforce gtx 260/28x owners with pciev2.0 compatible motherboard had notified they have 2.5 GT/S speed link for card (in system profiler -> pci cards)

normal link speed for pcieV2.0 is 5GT/s , 2.5GT/s is a speed of pcieV1, but, maybe its just cosmetic ?

here is part of output from lspci -vv, from pciutils pkg by joblo

01:00.0 VGA compatible controller: ATI Technologies Inc RV770 [Radeon HD 4850] (prog-if 00 [VGA controller])
Subsystem: ATI Technologies Inc Unknown device 0502
….
Capabilities: [58] Express (v2) Legacy Endpoint, MSI 00
….
LnkCap: Port #0, Speed 5GT/s, Width x16, ASPM L0s L1, Latency L0 <64ns, L1 <1us
ClockPM- Suprise- LLActRep- BwNot-
LnkCtl: ASPM Disabled; RCB 64 bytes Disabled- Retrain- CommClk+
ExtSynch- ClockPM- AutWidDis- BWInt- AutBWInt-
LnkSta: Speed 5GT/s, Width x16, TrErr- Train- SlotClk+ DLActive- BWMgmt- ABWMgmt-
Capabilities: [a0] Message Signalled Interrupts: Mask- 64bit+ Queue=0/0 Enable+
Address: 00000000fee00000 Data: 40a6
Capabilities: [100] #1002

Comments

  1. mark
    July 14th, 2009 | 11:25 pm

    I have a i7 p6t deluxe,2 saphire cards 1 is a 4850 1gig(is seen by mac as a 512mb card)and a 4870 1gig, 12 gigs of ram
    if i use the 4850 by it self it will parshaly boot, then give me a black screen. with the 4870 it sees both cards on slot 1, the 4850 has full features, but shows as having no monitors conected. I got this to work with both cards hooked up (no video on 4850) using the big radion kernel, momith kenel, and the 2000x kernels, and the moded open gl framework. I think the problem is that the 4050 is seen as a 512 mb card, or it is a pci-e problem

  2. Ricardo
    July 17th, 2009 | 7:31 am

    I get terrible performane on my LCD monitor with the Evga drivers. Funny cause my gtx 260 flies when I have my HDTV connected on the same leopard install.

  3. machinist
    August 10th, 2009 | 7:20 am

    Thanks for posting this. Finally managed my 3870 by DSDT, (to join ethernet and audio), and discovered it shows as a PCI card in system profiler, but at 2.5GT/s. Spent a while trying things to get it properly recognized, then with a successful Google found this entry. I read your blog regularly. It’s pinned to my Safari “Top Sites” display but I must have missed this last month. lspci -vv shows:

    LnkCap: Port #0, Speed 5GT/s, Width x16, ASPM L0s L1, Latency L0 <64ns, L1 <1usClockPM- Suprise- LLActRep- BwNot-

    LnkSta: Speed 5GT/s, Width x16, TrErr- Train- SlotClk+ DLActive- BWMgmt- ABWMgmt-

    My concerns that the card was not being used to its full potential are allayed. It seemed to be running right anyway…

    On the subject of inaccurate readings, I have feedback regarding your CPU ID tool, CPU-X. Comparing the results of your tool with Intel’s MacCPUID yield profoundly different results. Leopard apparently overclocks my already overclocked Q6600 from 3.2 to 3.6 by changing the multiplier from my bios set 8 to 9. Your tool reported the (old) smbios setting of 3.2. MacCPUID reports 3.6 (and has a button to push to read real time). When I reset the bios settings to a “normal” 2.x your tool still reports the old overclock, as does System Profiler. I just reentered what I wanted in the smbios and I’m good with that, and I check MacCPUID if I want an accurate reading on clock speed, so no worries. You just might want to check your clock speed with Intel’s tool.

    Thanks for blogging, and sharing your knowledge. You saved me hours if not days of fretting over an issue which appears to be a phantom.

  4. luyi
    November 8th, 2009 | 12:51 am

    My MOBO is p35c ds3r 2.5GT/S is right? but ROM Revision: nVidia GeForce 8500 GT OpenGL Engine, my card is HD 4830 VGA/DVI/HDMI
    ATI Radeon HD 4830:

    Name: ATY,Motmot
    Type: display
    Driver Installed: Yes
    Bus: PCI
    Slot: Slot-1
    Vendor ID: 0×1002
    Device ID: 0x944c
    Subsystem Vendor ID: 0x174b
    Subsystem ID: 0xe104
    ROM Revision: nVidia GeForce 8500 GT OpenGL Engine
    Revision ID: 0×0000
    Link Width: x16
    Link Speed: 2.5 GT/s

  5. PGHammer
    October 31st, 2010 | 11:20 pm

    Same applies to my HD5450 as well. Mobo is an ASUS P5G41-M LX2/GB (vanilla DSDT).

    Card is a Visiontek HD5450 (also VGA/DVI/HDMI)

    Name: ATY,Megalodon
    Type: display
    Driver Installed: Yes
    Bus: PCI
    Slot: Slot-1
    Vendor ID: 0×1002
    Device ID: 0x68f9
    Subsystem Vendor ID: 0×1545
    Subsystem ID: 0×5450
    Revision ID: 0×0000
    Link Width: x16
    Link Speed: 2.5 GT/s

  6. businessman9
    November 14th, 2010 | 9:00 pm

    My 5770 runs at 2.5 GT/s and half performance of windows 7

    cinebench 21.xx fps in OSX and 42.xx in windows7
    I tried to change boot files or use aty_init.kext but cant get it work at 5.0 GT/s

    i3-530 H55M-UD2H MSI5770cyclone1g with tonymac dsdt

  7. SLml2
    January 29th, 2011 | 4:56 pm

    Any solution for working 5.0GT/s link speed instead of 2.5GT/s?
    My mobo is a gigabyte GA-P55A-UD3 and Graphics Card is Gigabyte Gt 240 512mb DDR5.
    Stuck at working in half speed (2.5GT/s whereas should be 5.0GT/s)

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