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CF on x48 vs. CF on P45

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Last response: in Systems
September 6, 2008 5:40:25 PM

i'm looking to build a system in the next week or so.
any suggestions on whether it's worth the extra $130ish dollars to go with a
x48 motherboard?
if it's only a matter of a few hundred 3dmark points, i could care less.
but if it's like a night and day performance difference, i wouldn't mind shelling out the extra.
i'm going to be running everything on 1080p on my dell 2709w (yum!), with a 4850, most likely crossfire afterwards.
the p45 i had in mind is the asus pq5 pro
any links/advice would be great! would love to see some benchmarks
also, what brand is best for the 4850?
i'm leaning towards palit, because it comes with a dual slot cooler and is cheaper!

More about : x48 p45

September 6, 2008 5:50:39 PM

You can get a pretty good idea how the X48 (2x16 PCI-e lanes) shakes out against the P45 (2x8 PCI-e lanes)
in this review over at Legion Hardware
They also have X38 and P35 up for comparison so you have all the recent Crossfire chipsets covered.
September 6, 2008 6:03:48 PM

^ good benchmarks and more up to date then the tweaktown review.
Related resources
September 6, 2008 6:19:14 PM

You won't be doing CF unless you're monitor's resolution is high and in that case you gain by going the X48 route.
September 6, 2008 6:23:09 PM

so since i'm using a 1920x1080 27" monitor..x38/x48 is the only way to go?
will a p45 really be completely worthless at 1080p?
September 6, 2008 6:27:39 PM

WR2 said:
You can get a pretty good idea how the X48 (2x16 PCI-e lanes) shakes out against the P45 (2x8 PCI-e lanes)
in this review over at Legion Hardware
They also have X38 and P35 up for comparison so you have all the recent Crossfire chipsets covered.

i just read the review and seems like there's barely much of a performance advantage at 1920x1080.
or am i missing something?
it's like less than 1% more for $130 more
i'm confused!
September 6, 2008 6:34:16 PM

You may need 4870s or better GPUs to really start seeing a difference.
The 4850s don't seem to be powerful enough to limit the P45s. in CF.
September 6, 2008 6:54:52 PM

You're not as confused as you think - the 19x12 performance gap isnt very wide.
Here is the DX9 chart for World of Conflict - the other review had DX10 chart.

At 25x16 res the gap starts to widen but at 19x12 it's still under 10%
Devil May Cry 4 was about 5% in the Legion review.
Another P45 vs X48 review @ Tweaktown had a larger gap when they tested Crysis than Legion Hardware did.
September 6, 2008 7:29:19 PM

If you get a ASUS P5Q pro with two pcie slots at 8x or higher, then you will be fine. The X48/P45/X38/P45 chipsets make very little difference. I guess <3%.

There are better ways to spend the $130 difference in the motherboard.
1) Go to 4gb if you have not planned on it.
2) splurge on upgrading to a velociraptor
3) get a second small monitor
4) upgrade the cpu.

Also, I don't think the Palit 4850 has a dual slot cooler. The slot looks like one, but the air is not directed outside the case through the slots.
I do like vga cards with slot coolers, though. It really is the only good way to help the rest of the parts. Look at the ICEQ4 version from HIS. It looks like a good cooler. It costs a bit more, but you won't need an oem cooler.
September 6, 2008 7:58:32 PM

i think you will need 4870X2CF@2560x res with full AA and AF to see the real bandwidth difference. so its pointless getting 2 card when just game at 1920 as you still get smooth frame rate.
September 6, 2008 8:45:54 PM

so if i plan to run CF 4850's at 19x12 resolution the p45 won't limit this setup by much?
i want to spend less than 1k on my rig, a x48 puts me over the edge. also 130 can almost buy me a second 4850 lol

and this is the palit 4850 i'm thinking of

definitely a dual slot cooler on that thing, it's huge :D 
September 6, 2008 8:59:44 PM

also, will there be a 4850x2?
that would solve my problems...until i feel like CFing them :S
September 6, 2008 9:03:04 PM

I think your best price/performance option is P45 and 2x4850CF.

Actually that isnt the typical dual slot cooler that funnels hot air off the GPU and out the back of the case. That aftermarket model just dumps the hot air inside the case - although that isnt that big a problem for a well ventilated case.

A more traditional dual slot cooler. The shroud funnels most of the hot air out the back of the case.

September 6, 2008 9:16:27 PM

My point exactly WR2.

How do you get a photo to show up in the forum text?
September 6, 2008 9:22:01 PM

You only need to use the tags or just use the image button on the toolbar.

September 6, 2008 9:29:21 PM

ohhh thank u, i get it now haha.
aftermarket cooler is what i was getting at. anything is better than stock am i rite? haha
i'll be using hte cm 690 with all stock fans+optional fans up and running, so ventilation should be solid.
will there be a 4850x2 soon?
and with nehalem coming out soon...should i be buying a system now with all the deals going on. or will it drop even more after nehalem drops in the next few months?
i won't buy a nehalem either way, but should i wait for it, so the prices for p45 drop even more? it already seems really really cheap and good deals like free shipping
September 6, 2008 9:32:10 PM

4850x2 - nobody knows. A 4850X2 might undercut 4870 & 4870X2 sales so I dont think there is any rush to bring one to market.

You have a great case and it won't have any problem with the aftermarket style GPU coolers.
September 6, 2008 10:35:38 PM

+1 on the P45+HD4850CF.

there are alot of AMD cards spaming the market fairly soon just like Nvidia did with their 8-9series.

lower end 4xxx,4650,4670,4850X2........
September 7, 2008 4:41:27 AM

As far as I understand it, the P45 boards have one x16 slot and one x8, however these are PCI-E 2.0 standard, so a PCI-E x16 2.0 slot bandwidth would have the same effective bandwidth as an x32 slot of the old standard, and a PCI-E x8 2.0 slot would have the same bandwidth as an old x16 slot.

Basically what I'm saying is that if you use a P45 board to crossfire you will be running on the equivalent of one PCI-E 2.0 and a PCI-E x16, so you shouldn't run into any problems just yet, since cards are not able to saturate a regular x16 slot. (unless the HD 4870 X2 managed to do this, which I doubt.)
September 7, 2008 8:03:05 AM

Sorry if I'm stupid, but you guys are saying at his screen resolution, running a x48 nb will see little/no gain vs running a p45 nb w/ 2 hd4850's?

im building a new gaming rig.. wanted to buy 1 4850 and then another one later when i got more money.. i was gonna run the x48 chipset but they really are more expensive.. ill be running a 22" 1680x1050 screen..

you guys are saying, go p45 correct?
September 7, 2008 9:16:14 AM

Most benchmarks concerning chipset crossfire performance are absolute bull. If you want full crossfire on the intel platform you will need a X38/X48. The usage of bandwidth rapidly increases as more powerful cards are used.
If you're only going to use 4850 cards at such a lowly resolution then you won't need a high end chipset, P45 will serve you fine.
September 7, 2008 2:39:32 PM

WR2 said:
You can get a pretty good idea how the X48 (2x16 PCI-e lanes) shakes out against the P45 (2x8 PCI-e lanes)
in this review over at Legion Hardware
They also have X38 and P35 up for comparison so you have all the recent Crossfire chipsets covered.

dirtmountain said:
^ good benchmarks and more up to date then the tweaktown review.

The difference in results has nothing to do with being up to date. They used different settings. The tweaktown review use max settings that stress the cards, and pcie bus, to the limits, legion hardware review, for the most part, does not. Take the Crysis benchmark, for example:
The legion review use high settings, dx9, with AA off, AF off. Tweaktown review use Very High settings, dx10, AA and AF on. Tweaktown review gets significantly lower fps. The more stressed those cards run, the more they have to coordinate, increase traffic across pcie bus. More traffic certainly means more bottlenecking.

AA and AF is an especially big factor in pcie bus bottlenecking:

As you can see from Legion's World in Conflict bench, which unlike for Crysis, is tested on dx10 with aa/af turned on, there's less difference compared to Tweaktown's results:
September 7, 2008 4:00:47 PM

dagger said:
The difference in results has nothing to do with being up to date. They used different settings.

They used different ATI drivers - Cat 8.6 for TT review and Cat 8.7 for LH review.
Tweaktown used Crysis 1.1 patch (even though 1.21 has been out since March). LH doesnt specify what ver of Crysis was used but they had used 1.2 in earlier reviews.

Tweaktown was on v1.1 for Unreal Tournament 3 and LH was on v1.2

I think that counts for towards being more up to date.

Spending some extra $$$ to get that little bit extra performance has to be a personal decision.
E8400 or E8600 CPU? DDR2 800 or DDR2 1066 RAM? Same as the P45 vs X48 decision.
P45 and 2x4850CF @ 16x10 and 19x12 seems like a good value to me. But then Im perfectly happy setting AA @ 2 instead of 4 or drop the graphics quality a notch (from insanely high to very high for example) if that is what is needed to get a few extra FPS to get a game play comfortably for me.

September 7, 2008 9:17:11 PM

At the high end, smaller gains in performance start costing more and more as you progress. DDR3, X48, multi GPU, aftermarket cooling: air->water->LN2, the list just goes on and the facts remain the same. :) 
September 8, 2008 1:21:40 AM

emp said:
Solution is kinda simple then, don't settle for a P45 board, but don't pay the X48 price... Buy an X38 board for $185:

DFI LANPARTY DK X38-T2R LGA 775 Intel X38 ATX Intel Motherboard - Retail

i might just have to do to do that lol.
it's on ncix,

so here comes another question....what's the differences between x38 and x48???
faster fsb? ddr3 support?
September 8, 2008 1:40:55 AM

X48, if I recall correctly, is basically a shrink of the X38, with "official" 1600 FSB support (even though this is a breeze for the X38 to do). Basically a way for intel to produce more northbridges for less money and still be able to charge you a premium over the X38 boards.

If you compare the ASUS Rampage formula (X48 board) vs the DFI X38 I showed you, you'll see that the only real difference is the "official" 1600 FSB support and 2 gigabit ethernet ports instead of one, but the difference in price is $130 CAD.
September 8, 2008 4:19:30 PM

The number of ethernet ports have nothing to do with the northbridge used! X48 is not a shrink of X38 either. Emp you disappoint me.

X48 are basically X38s that have been binned for higher FSB speeds with lower voltages. They are built on the same 90nm process as X38s. Apart from needing slightly lower voltages while OCing and reaching higher OCs in average they're the same chip.
September 8, 2008 4:25:46 PM

Oh shoot... I was 95% sure it was a die shrink, thanks for the info. I think I assumed that it was a shrink because an article stated that the X48 ran slightly cooler than the X38. And the point I was trying to make is that the Rampage formula had 2 ethernet ports over the DFI X38-T2R, which is all that it has going for it at the moment.
September 8, 2008 7:12:54 PM

Yeah X48s are running cooler because they're specially picked (read binned) X38s. The Rampage Formula is not only different by ethernet ports.

It has 8 fan connectors and the fan speed can be adjusted by software or in the bios (they can be set at a certain speed and ramp up when the motherboard reaches a certain temp). This pretty much eliminates the need for an expensive fan controller.

The Rampage also comes with Asus' LCD poster which is useful when overclocking to read which component caused the OC fail, it saves more time than doing things the slow way.

Those are just 2 differences in addition to the better chipset.

DFI are a respectable enthusiast brand but Asus' Rampage Formula is simply better.

Now back to the main topic. The OP is more concerned about CF performance and in that case the DFI will definitely deliver and at a lower price so I'll recommend it.