Picking Crossfire Mobo

[huilun02]

I intend to buy a HD4870 along with a good & stable mobo with Crossfire. The mobo has to have at least two pci-e 2.0 x16 slots (at x16+x8 or x16+x16), and support for DDR2. I'll start off with one card first and then add another for Crossfire when I feel like it.

I guess i'm pretty much left with the P45, X38, and X48 chipsets. I'm looking in particular at the Asus ROG boards for their excellent overclocking abilities. Probably the best board for me would be the Rampage Formula, but I hear it's not any much better than the Maximus or Maximus II, to be worth its price.

So please I need help in choosing a mobo. All comments and opinions are very much appreciated.

 

[aevm]

P5E Deluxe (X48), GA-X48-DS4. There's really no need to spend $300+ on a motherboard.

 

[marshmellow1991]

well, im currently using a DFI lanpart DK X38 T2rb. pretty decent if you ask me, MASSIVE overclocking options, 2 pcie x16, and.....*looks into case*...3 pci slots. nice cooling solution for nb too..
http://www.newegg.com/Product/Product.aspx?Item=N82E16813136051

 

[huilun02]

I already have an Intel C2D E8500 Wolfdale (45nm) which I plan to work with the mobo, so is that going to affect my choice of boards? I'm going to OC my board 24/7 but not by a lot. Currently my E8500 is doing 8x400MHz in sync with twin sticks of 1GB DDR2 800Mhz (stock E8500 runs at 9x333MHz) on an Abit P35 Pro. I agree the P35 is good but its PCI-E 1.0 x16 slots are really limiting my gaming experience.

 

[aevm]

On a P35, the second slot runs at 4x in Crossfire, and it's PCI-E 1 too. On a P45, it runs at 8x, and it's PCI-E 2. That's 4 times the bandwidth, and it makes a huge difference. On an X38 or X48, it runs at 16x, PCI-E 2, i.e. twice as much bandwidth as on P45 and 8 times as much as on P35. Surprisingly, that doesn't make a huge difference. For example in your case a P45, X38 or X48 would be smart choices, with P45 < x38 < x48 as price and performance in Crossfire go. Something like Asus P5Q Pro or GA-EP45-DS3R, for example, around $150, would be almost as good as a P5E Deluxe X48 or GA-X48-DS4, at least at 1680x1050 or less. If you have a 24" or bigger monitor, the P45 starts to get bottlenecked by the 8x speed, and it falls behind the X38/X48 . That's happening with HD 4850 cards, and (I'm assuming) in a bigger measure with HD 4870 and HD 4870X2. For HD 3870 or less I don't think it matters at all.

Here's an article with some numbers:
http://www.legionhardware.com/document.php?id=761&p=8

As for the CPU: in general, E8500 should work nicely with any P45/X38/X48 and can do 9.5*400MHz with DDR2-800.

 

[jamesgoddard]

I already have an Intel C2D E8500 Wolfdale (45nm) which I plan to work with the mobo, so is that going to affect my choice of boards? I'm going to OC my board 24/7 but not by a lot. Currently my E8500 is doing 8x400MHz in sync with twin sticks of 1GB DDR2 800Mhz (stock E8500 runs at 9x333MHz) on an Abit P35 Pro. I agree the P35 is good but its PCI-E 1.0 x16 slots are really limiting my gaming experience.

Do you have xfire currently - if not I doubt that the single PCI-e 1 x16 slot is causing you any performance drop off that you can measure...

And if you really do want to get xfire 4870 - just keep the current mobo and get a 4870x2 now - costs less and performs a little better than 2 single 4870's...

The P35 is really all you need – unless you have cash to burn

 

[aevm]

Yeah, you could reuse the IP35Pro with a HD 4870 X2, excellent point.

 

[huilun02]

I'm currently using a single OEM-locked 8500GT on my IP35 Pro. I had originally intended to get a very good video card or two to replace it, but then I realized I face the problem of needing PCI-E 2.0 slots to get the full power out of modern gaming cards (from the 8800GT all the way up to the HD4870 and GTX280). So I decided to get a new mobo to open the doors to a true enthusiast's world. Nvidia boards for SLI will cost too much, so I turn to Intel chipsets that offer Crossfire for comparable performance but at lower cost.

I intend to get twin HD4870's on a X38 or X48 board, but currently I cant afford 3 of such high end products, so i'll get the board and one HD4870 first, and Crossfire later with another card purchased. At first I thought the Rampage Formula was the answer but upon further inspection I saw that I could do away with the pricey overclocking features since i'm not going to overclock much. As of now I am really considering the ASUS P5E Deluxe because it has the X48 to give the best out of Crossfire but without the high(er) price.

By the way, wouldn't the HD4870 X2 bottleneck on the P35's PCI-E 1.0 slot? And wouldn't it run hotter since its two GPU to one fan?

Anyway, if anyone sees a X48 mobo better than the P5E Deluxe at comparable price, please do tell me. Thanks.

 

[dagger]

On a P35, the second slot runs at 4x in Crossfire, and it's PCI-E 1 too. On a P45, it runs at 8x, and it's PCI-E 2. That's 4 times the bandwidth, and it makes a huge difference. On an X38 or X48, it runs at 16x, PCI-E 2, i.e. twice as much bandwidth as on P45 and 8 times as much as on P35. Surprisingly, that doesn't make a huge difference. For example in your case a P45, X38 or X48 would be smart choices, with P45 < x38 < x48 as price and performance in Crossfire go. Something like Asus P5Q Pro or GA-EP45-DS3R, for example, around $150, would be almost as good as a P5E Deluxe X48 or GA-X48-DS4, at least at 1680x1050 or less. If you have a 24" or bigger monitor, the P45 starts to get bottlenecked by the 8x speed, and it falls behind the X38/X48 . That's happening with HD 4850 cards, and (I'm assuming) in a bigger measure with HD 4870 and HD 4870X2. For HD 3870 or less I don't think it matters at all.

Here's an article with some numbers:
http://www.legionhardware.com/document.php?id=761&p=8

As for the CPU: in general, E8500 should work nicely with any P45/X38/X48 and can do 9.5*400MHz with DDR2-800.

That benchmark is somewhat misleading. Take their Crysis benchmark, for example, which shows minimum difference between pcie1.1x4(p35) and pcie2.0x16(x48). They run the tests in DX9, with both AA and AF turned off. AA and AF are memory hungry functions that increase pcie bus load a lot in cf. The High setting using DX9 also saves bandwidth. Most people with cf rig would want AA. And everyone would want AF, as it simply looks too different without it.

Benchmarks using max settings in DX10 produces a much bigger difference.
http://www.tweaktown.com/articles/1472/7/page_7_benchmarks_crysis/index.html

The lower settings used in Legion Hardware bench are not enough to bottleneck pcie bus, the higher settings used in the TweakTown bench are. Future games will be heavier and cause bigger load on pcie bus. Even if you don't face the bottleneck now, it's only a matter of time before you reach that crossing.

 

[jamesgoddard]

The chip to chip comms in the 4870x2 is PCIe2 - even if the mobo if PCIe1...

Also the 1GB memory per GPU would most likely help alot in the high settings you posted...

The tweaktown article is not valid when considering the 4870x2

 

[huilun02]

I've noticed that there actually no reviews (wtf!?) or good comments on the P5E Deluxe. What's wrong with it? Why is everyone shunning it? If it's really that bad then please refer me to another good x48 mobo, perhaps those of Gigabyte's, because I dont really need to spend $300+ on the Rampage.

 

[huilun02]

I've decided to get a new x38 or x48 mobo, most probably an x48 one. I need recommendations for a X48 board.

Take a look at my other thread:
http://www.tomshardware.com/forum/252765-30-asus-deluxe-what-wrong#t1786488

 

[kanthu]

On a P45, it runs at 8x, and it's PCI-E 2. That's 4 times the bandwidth, and it makes a huge difference. On an X38 or X48, it runs at 16x, PCI-E 2, i.e. twice as much bandwidth as on P45 and 8 times as much as on P35.

Is it that both X38 & X48 mobos have PCIe Gen2.0 slots?
I thought only X48(& P45 of course) has Gen 2.0 slots whereas X38 has Gen1 slots

 

[aevm]

X38 and P43 also have PCI-E 2.0 slots. So does 790FX for AMD.
Examples:

ASUS P5E LGA 775 Intel X38
http://www.newegg.com/Product/Product.aspx?Item=N82E16813131219

GA-EP43-DS3L
http://www.newegg.com/Product/Product.aspx?Item=N82E16813128347