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 Posted: Wed Jul 30, 2008 1:54 pm Post subject: Gigabyte GA-EG45M-DS2H is limited to PCIE x4 |
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I don't know if people are aware of this, but it appears that Gigabyte's new G45 board suffers from a significant design weakness.
According to the board's block diagram, the main PCIE x16 slot is attached to the southbridge instead of the northbridge. As a result, it offers only 4 lanes of electrical connectivity and lacks support for PCIE 2.0 signalling.
I don't know if this bottleneck can already hold back today's high-end cards (I guess we'll know soon enough, once reviews are out) but one eighth the theoretical bandwidth sounds just bad to me. People who consider this board should be forewarned that they won't get much in the way of GPU upgrade path.
This is quite a shame, because the board has a very nice feature set, and if it weren't for this limitation it could serve as a long-lasting platform for GPU upgrades.
Source: renethx from AVSForum.
http://www.avsforum.com/avs-vb/showthread.php?p=14376354#post14376354 |
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Firetech
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Joined: 16 Dec 2005
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Location: Sydney, Australia
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| Posted: Wed Jul 30, 2008 2:35 pm Post subject: Re: Gigabyte GA-EG45M-DS2H is limited to PCIE x4 |
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| line wrote: | I don't know if people are aware of this, but it appears that Gigabyte's new G45 board suffers from a significant design weakness.
According to the board's block diagram, the main PCIE x16 slot is attached to the southbridge instead of the northbridge. As a result, it offers only 4 lanes of electrical connectivity and lacks support for PCIE 2.0 signalling.
I don't know if this bottleneck can already hold back today's high-end cards (I guess we'll know soon enough, once reviews are out) but one eighth the theoretical bandwidth sounds just bad to me. People who consider this board should be forewarned that they won't get much in the way of GPU upgrade path.
This is quite a shame, because the board has a very nice feature set, and if it weren't for this limitation it could serve as a long-lasting platform for GPU upgrades.
Source: renethx from AVSForum.
http://www.avsforum.com/avs-vb/showthread.php?p=14376354#post14376354 |
Thanks, the website product specification clearly states it's an x4 slot only.
http://www.gigabyte.com.tw/Products/Motherboard/Products_Spec.aspx?ClassValue=Motherboard&ProductID=2877&ProductName=GA-EG45M-DS2H
| Quote: | Expansion Slots
1. 1 x PCI Express x4 slot (Refer to the VGA device support list.)
2. 1 x PCI Express x1 slot
3. 2 x PCI slots |
I think the Asus P5Q-EM will be the board to go with at this stage.
http://www.asus.com/products.aspx?l1=3&l2=11&l3=761&l4=0&model=2413&modelmenu=2
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dCrypt
Joined: 15 Jan 2003
Posts: 40
Location: Madrid, Spain
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| Posted: Mon Aug 04, 2008 12:28 pm Post subject: |
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I've just read in Asus Forums that, due to G45 limitations, Gigabyte decided to change the 'natural' design (PCIe x16 2.0).
In case a PCI-e board is inserted (whether it's a VGA or not), the IGP is automatically disabled. The problem is when you want to use a PCI-e x4 card (ie RocketRaid SATA controller).
http://vip.asus.com/forum/view.aspx?id=20080729234236140&board_id=1&model=P5Q-EM&page=1&SLanguage=en-us
So, it seems to me that Gigabyte designed this board considering that the IGP should be used all the time, and eventually you can use a x4 PCI-e upgrade board, with some kind of VGA support in that slot.
Last edited by dCrypt on Mon Aug 04, 2008 11:00 pm; edited 1 time in total |
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Greg F.
Joined: 23 Nov 2005
Posts: 354
Location: Seattle
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| Posted: Mon Aug 04, 2008 5:56 pm Post subject: SUPERMICRO |
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Supermicro's ATX entry in the G45 chipset does not have a DVI connection, only D-Sub and HDMI. They don't include a DVI adapter for those who choose to eschew HDMI. To me this is an oversight that anyone on this forum could have told them was boneheaded. But, they included two (2) 1394 headers!
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| Posted: Thu Aug 07, 2008 8:58 am Post subject: |
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| dCrypt wrote: | | I've just read in Asus Forums that, due to G45 limitations, Gigabyte decided to change the 'natural' design (PCIe x16 2.0). |
Thanks for posting that link. I wasn't aware of that limitation. It helps to know the reason behind Gigabyte's decision because we can now suggest a better compromise.
| dCrypt wrote: | | In case a PCI-e board is inserted (whether it's a VGA or not), the IGP is automatically disabled. |
It seems there's an exception to this rule. If you install a PCI-E x1 card that is not a graphics card, the IGP will continue to work. In all other cases the IGP will become disabled as you said.
I don't understand, however, why Gigabyte didn't come up with a better workaround. It's an important goal to allow x4 cards to be used without tripping the IGP, but it doesn't have to come at the expense of the graphics upgrade path. If it were up to me, I would leave the PEG slot with the full x16 2.0 interface, and route the southbridge's x4 group to another place. Perhaps to the x1 slot at the bottom of the board. It could become an unterminated x4 slot. Here's an example of an unterminated x4 slot on Gigabyte's GA-MA69G-S3H board. It's the one colored in orange:
Does anyone see a problem with this approach? |
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Elvellon
Joined: 09 Dec 2007
Posts: 104
Location: Moscow, Russia
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| Posted: Thu Aug 07, 2008 11:19 am Post subject: |
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AFAIK PCI-E 1.0 x8 bandwidth is enough for cards like 8800 GT (x4 setting them back like 20%). PCI-E 2.0 x4 is equal to 1.0 x8, so if your graphics card supports 2.0, you should be OK.
Too bad that it still feels like Giga cheated.
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peerke
Joined: 21 Aug 2003
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| Posted: Thu Aug 07, 2008 11:31 am Post subject: |
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| line wrote: | | Does anyone see a problem with this approach? |
Maybe getting Gigabyte to implement it?  |
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dCrypt
Joined: 15 Jan 2003
Posts: 40
Location: Madrid, Spain
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| Posted: Fri Aug 08, 2008 12:42 am Post subject: |
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| Elvellon wrote: | | PCI-E 2.0 x4 is equal to 1.0 x8, so if your graphics card supports 2.0, you should be OK. |
The problem is that PCI-e x16@x4 in this mb seems to be electrically routed to the southbridge (PCI-e v1.0) instead of the northbridge (PCI-e v2.0). Your have half the bandwith, even if your graphics card supports 2.0.
| Elvellon wrote: | | Too bad that it still feels like Giga cheated. |
At least, they are not clear enough. Did somebody review their mb manual? |
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Elvellon
Joined: 09 Dec 2007
Posts: 104
Location: Moscow, Russia
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| Posted: Fri Aug 08, 2008 4:20 am Post subject: |
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| dCrypt wrote: | | The problem is that PCI-e x16@x4 in this mb seems to be electrically routed to the southbridge (PCI-e v1.0) instead of the northbridge (PCI-e v2.0). |
Ouch then!!
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merlin
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| Posted: Fri Aug 08, 2008 11:21 am Post subject: |
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I'd definitely pick another board if you want g45 now with plugin gpu. Hopefully they'll make a proper g45 with a pci-e 2.0 16x slot for a future model. I think realistically this board is specifically for integrated graphics, it should NOT be used for discrete at all. The problems of adding a 16x probably stem from having hdmi + dvi + vga. Far too overkill if you're going discrete.
If your goal is integrated graphics for a htpc, this board is perfect. If your goal is adding your own card, wait for a model that doesn't have 3 video outputs from integrated, all useless if you're going discrete.
Actually that makes me wonder one thing, except for microatx/mini-itx, why would anyone pick a g45 for discrete?
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