VOGONS


First post, by W.x.

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Hello. To this date, I've thought, that i945gz motherboards do not have PCI express slot, well but today I've come across GA-945GZM-S2 and was quite confused, that it has full PCI express slot. So I've checked internet, and found out, where is the catch, it is interpreted through southbridge, and has only 4 lanes instead 16.
So I was thinking, how fast and compatible is this solution, in comparation to full i945 chipset, that has x16 lanes connected through northbridge.

Is it same compatible, or I can experience problems with PCI express graphic cards.
Main question... how much slower it is, in comparation to full x16 slot. I mean, with typical fast Pentium 4 in it, lets say 3 Ghz Pentium and Windows XP games of 2005-2008 era, do you experience any major slow down with lets say 7900 GTX?

Reply 1 of 5, by pentiumspeed

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The x4 lane is from southbridge if desired but not on this one you have for this model. The single PCIe slot is real x16 lanes from the northbridge. Checked the chipset wiki and gigabyte.

If motherboard maker wanted more lanes, they add second PCIe x4 slot from the southbridge, common practice even now.

Cheers,

Great Northern aka Canada.

Reply 2 of 5, by Horun

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pentiumspeed wrote on 2021-05-05, 00:01:

The x4 lane is from southbridge if desired but not on this one you have for this model. The single PCIe slot is real x16 lanes from the northbridge. Checked the chipset wiki and gigabyte.

If motherboard maker wanted more lanes, they add second PCIe x4 slot from the southbridge, common practice even now.

Cheers,

Yeah you are correct ! checked the datasheet and has a full 16x PCIe from northbridge, have seen some early boards where they route the lanes to two PCIe slots where each is just 8x but the GA-945GZM is not done that way.

Hate posting a reply and have to edit it because it made no sense 😁 First computer was an IBM 3270 workstation with CGA monitor. 🤣 Second computer a 286 12Mhz with real IDE drive ! After that came 386, 486, Pentium, P.Pro and everything after....

Reply 3 of 5, by W.x.

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Here in specification, there is mentioned something, that I've thought is meant it is x4
So maybe slot looks like full x16 slot, it has only 4 lanes?

https://www.gigabyte.com/Motherboard/GA-945GZ … S2-rev-21/sp#sp

Expansion Slots1 PCI Express x 16 slot (@x4)
3 PCI slots

Reply 5 of 5, by Horun

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Odd ! Intel lists the 82945GZ as 16x PCIe https://ark.intel.com/content/www/us/en/ark/p … controller.html
but the datasheet says: PCI Express Graphics Interface (82945G/GC/P/PL only)
they had a board D945GZCC2 based on it but no other tech docs found, maybe it had issues with PCIe from the northbridge or all the lanes were dedicated to the onboard 950 graphics ????.

Hate posting a reply and have to edit it because it made no sense 😁 First computer was an IBM 3270 workstation with CGA monitor. 🤣 Second computer a 286 12Mhz with real IDE drive ! After that came 386, 486, Pentium, P.Pro and everything after....