X48 vs P45 setup - Need advice

[sarotara]

I'm giving away my current system (Athlon X2 64 3800+/ATI X1950/2GB RAM) to my younger, and "college-poor", brother, and I've been looking at the pros and cons of getting an X48 vs a P45 based system. I would be keeping my current case, a 620 W Corsair PSU, a 24" Dell widescreen LCD panel, and a 500GB SATA drive. The computer would be used primarily for gaming. I don't bother with overclocking unless the computer is getting old and I'm trying to squeeze some more useful life out of it.

I've been debating on whether I should get an X48-based system versus a P45-based system for a couple of weeks now and I'm still not sure what to do... At a 1920 x 1200 resolution dual ATI video cards in a 16x/16x Crossfire setup look really great, but the price is not so good mainly due to the high cost of decent X48 motherboards (DFI X48-T2RSB or Gigabyte GA-X48-DS5, both around $225-250). The idea would be to get an ATI Radeon 4850 now, and when the need arises buy another ATI Radeon 4850 and use them in a Crossfire setup.

A P45 setup would allow me to spend less money on a motherboard (Gigabyte GA-EP45-UD3P or an Asus P5Q Pro, $100-140) and more money on a video card. 16x/8x Crossfire doesn't work quite as well as it does at 16x/16x, unforunately. I would probably buy an ATI Radeon 4870 now, but I'm not sure what upgrade path I would take in the future with this kind of setup.

So I have the following (in addition to an E8400 + 4GB DDR2 RAM):

X48 Setup
- Now (Video Card): ATI Radeon 4850
- Future (Video Card): 2 x ATI Radeon 4870 (Crossfire)

P45 Setup
- Now (Video Card): ATI Radeon 4870
- Future (Video Card): ???

Any suggestions or insights into this whole X48 vs P45 thing would be really appreciated.

 

[ther00kie16]

Could just get a 4870x2 in the future if you are that worried about performance lost on 16x+8x. The 4870 will probably last you a year or more, by which time there will be newer generations.

 

[DSF]

When in doubt, go with the single card setup.

 

[DaveSimmons]

With the cheaper motherboard you have much better video performance at 19x12 now, and can always get an x2 card later.

Spending the extra $100+ for future-proofing (and downgrading your video to do it) is a waste of money.

 

[Denithor]

X48 versus P45 -- no differences for crossfire performance. PCIe 2.0 x8 gives the same bandwidth as PCIe 1.1 x16 (neither of which are saturated yet by today's cards) so the P45 gives the same performance in crossfire mode as the X48 board. Just get a P45 with two PCIe slots (P5Q Pro) if you want the option to add a second card in the future.

Go for the better card now and add another later when it slows down or upgrade to a new single card, whichever makes more sense then.

 

[DSF]

Originally posted by: Denithor
X48 versus P45 -- no differences for crossfire performance. PCIe 2.0 x8 gives the same bandwidth as PCIe 1.1 x16 (neither of which are saturated yet by today's cards) so the P45 gives the same performance in crossfire mode as the X48 board. Just get a P45 with two PCIe slots (P5Q Pro) if you want the option to add a second card in the future.

Go for the better card now and add another later when it slows down or upgrade to a new single card, whichever makes more sense then.

I thought the X48 boards operated at the full PCI-e 2.0 x16.

Either way, I don't think the X48 is the right choice here.

 

[sarotara]

Thank you for all the replies. All excellent points about the X48. I have to disagree with Denithor on the 16x/16x vs 16x/8x Crossfire however... X48 boards have two PCI Express 2.0 16x slots, not PCI Express 1.1. Additionally, at higher resolutions (1920 x 1200 and up) there is a fairly significant difference in game performance between 16x/16x and 16x/8x Crossfire setups. I'll go with the P45 setup and a better video card. Thanks again!

 

[nadirshakur]

When you say 16x/8x, do u mean that it does 8x when in dual mode and 16x when it's in single? Or do you mean one slot works at 16 and the other at 8, and what happens to the one that is running at 16 when u are in dual mode, does it go down?

 

[sarotara]

To the best of my knowledge, this is how Crossfire works. On the X48 chipset both slots are PCIe 2.0 16x and support CrossFireX at the 16x link speed. P45 chipsets also have two PCIe 2.0 16x slots, but they only support CrossFireX at the 8x link speed. So yes, when I said 16x/8x I meant to say 16x in single and 8x in dual mode.

 

[nadirshakur]

Just curios Denithor, if you may explain on your post. Why do you think that the performance would be the same for 8x and 16x crossfire? 8x is still not a bottleneck for any of the cards out there? Or Is the performance gain not significant enough?

 

[Reyals140]

Originally posted by: sarotara
Thank you for all the replies. All excellent points about the X48. I have to disagree with Denithor on the 16x/16x vs 16x/8x Crossfire however... X48 boards have two PCI Express 2.0 16x slots, not PCI Express 1.1. Additionally, at higher resolutions (1920 x 1200 and up) there is a fairly significant difference in game performance between 16x/16x and 16x/8x Crossfire setups. I'll go with the P45 setup and a better video card. Thanks again!

Reviews I've been able to find say there is not much a difference between 8x and 16x...
http://www.legionhardware.com/document.php?id=761&p=1
http://www.ocforums.com/showthread.php?t=571156

 

[sarotara]

Reyals140, try this one: http://www.legionhardware.com/document.php?id=761&p=0

 

[DSF]

Originally posted by: sarotara
Reyals140, try this one: http://www.legionhardware.com/document.php?id=761&p=0

Even that shows at most a 10% difference between 16x and 8x at 19x12, and generally much less than that. In the instances where the difference is close to 10%, both setups were over 60 FPS, so it hardly matters.