Why I will NEVER go back to crossfire or sli!

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goldsauce

goldsauce

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Just a couple of hours ago I was comparing what happens if I disable crossfire in the catalyst control panel and I found that my god damn games run much smoother and better fps when crossfire is DISABLED! I was shocked at first and now I am furious, because 80% of all of my games work better with crossfire disabled, so now I have taken out my other 7850 and it will be up on ebay tomorrow, let me just say this to anyone looking at getting crossfire, don't get your hopes up! Sure maybe 7850s in crossfire run better on BENCHMARKS but only on the damn synthetic benchmarks you get crazy 100% scaling but once you go in a damn game it turns into rubbish.
 
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manofchalk
Your PCI-Express bandwidth was the bottleneck, not the CPU.

Imagine you have a road 32 lanes wide and you have 32 cars driving abreast, each in a lane. Say that every second 32 cars can travel down this road.
Suddenly reduce that road to four lanes and you still have the same number of cars to get through, you can only get 4 cars through a second. Obviously everything is going to slow down because the road isnt as wide.

That is what you have done by putting in a 7850 on a PCI-2 4x slot, effectively limited the width of the road that the graphics cards can use to communicate with the CPU. That is why you have horrible performance in Crossfire.
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goldsauce

goldsauce

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Is that why when I took out once card, I started getting 15-25 more FPS...
 
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unksol

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That's simply not true. An occasional game will have issues before it is patched, or the drivers are updated. And of course crossfiring midrange cards is silly when you should just get a 7970. but there is clearly something wrong with your system. If you would like to rant instead of fixing it that is of course your prerogative

If you'd like to come back and ask for help nicely and provide some actual info maybe someone will bother to spend their time. Just for starters its pretty ridiculous to have a low end i3 driving a crossfire setup.
 
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MatildaPersson

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Yes. Because low range cards scale horribly in Crossfire/SLI and your system also bottlenecks it, thanks to a slow CPU and a motherboard not ideal for running more than one GPU.

You need a much better CPU and one good GPU (only SLI/Crossfire great GPUs), half as much RAM as you have, I'd have gotten a smaller HDD, but eh, they are cheap, a motherboard designed more for multi-GPUs if you want to go down that road, and a larger PSU would be nice -- 700watts is kinda cutting it close for two GPUs, as you want to be at about 50-70% of your available wattage for peak efficiency.
 
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unksol

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The 7850 is not a low range card and scaling is near 100%. He is NOT CPU bottlenecked right now, but might be if it were working. The system isn't even pulling 500W, 700W is PLENTY.

It is a pretty poorly thought out system, which is probably why he's having issues. he doesn't seem to know what he's doing. And if the newegg specs on the board are right

PCI Express 2.0 x16 2 (x1, x4)

NO WONDER it doesn't work right
 
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JackNaylorPE

JackNaylorPE

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Another anecdotal experience that is in complete contrast w/ reality. Upstairs I can hear games being played on the following:

Son No. 2 - Single 580
Son No. 3 - Twin 560 Ti's

Two 560 Ti's (Asus DCII TOP) for $400 outperform the single 580 (EVGA FTW) by 40% .... a mark which is echoed by dozens of published reviews.

Simple Rules of SLI / CF

1. No sense going that way if the rest of your system will bottleneck it.
2. Microstutter is NOT on issue with mid-range ==> high range cards ($200 and up).
3. No more than 2 cards in CF.
4. Power Supply must be beefy enough and must supply stable voltages (1% variation) if you want the highest overclocks.
5. SLI / CF options with mid range cards consistently have a lower cost per frame that the top tier single card solution.
 
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MatildaPersson

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The 7850 isn't high-range, either. I said it was poor-to-mid originally, in any case.

They are CPU bottle-necked, as that old i3 will never allow a dual GPU setup to perform anywhere near the way it should.

Pulling 500 watts out of a 700 watt PSU is bad; it's inefficient, so the PSU works harder, wastes more electricity and creates mroe heat. Somewhere around 60% of the PSU's rated limited is the sweet spot for efficiency.

But yes, that motherboard has been mentioned as being a large problem. While it *can* do Crossfire/SLI, it really shouldn't.

As an aside: Radeon cards (Crossfire) is much more prone to microstutter than Nvidia cards (SLI). I don't know why, but every test, including those on this site, report this issue.
 
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goldsauce

goldsauce

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Actually this board has PCI Express 3.0 x16 and I just put in my brothers 7970 into my system and it seems that the 7970 outperformed my 7850s in crossfire by a lot so I don't see much CPU Bottlenecking but I am planning on getting a i7 once I can afford one.
 
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MatildaPersson

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That motherboard allows for PCI Express 3 x16 when using ONE graphics card. As soon as you add a second, they drop it way down.

There's a reason it's the cheaper, "mobile" variant of the original.
 
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manofchalk

manofchalk

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You have a PCI-3 16X slot and a PCI-2 4x slot. By Crossfiring your cards your bottlenecking both cards to PCI-2 4x bandwidth.
Thats why your getting horrible performance with Crossfire enabled. You need to properly plan out your system before you get multiple cards.
 
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goldsauce

goldsauce

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Well, I might just save up for a i5 or i7 and a maybe wait for the prices of 7970 go down and just buy one but guys with crossfire or sli don't get mad this is just my opinion and I am sure a lot of you guys with crossfire or sli have awesome rigs.
 
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JackNaylorPE

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Matilda is right.

Interesting , albeit misleading, feature list

http://www.newegg.com/Product/Product.aspx?Item=N82E16813157306 Details Tab

Features:

1 x PCIe 3.0 x16 Slot, Supports AMD Quad CrossFireX , CrossFireX

Expansion Slots:

PCI Express 3.0 x16 = 1
PCI Express 2.0 x16 = 2 (x1, x4)
PCI Express x1 = 1
Click to expand...


You simply ain't doin' CF w/o two x8 PCI-E slots

The reason the 7970 works better is it is that it was working with x16 bandwidth
The reason the 7850's worked poorly is that they were working with x4 bandwidth
 
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manofchalk

manofchalk

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No, its your uneducated and ignorant opinion.
Crossfire/SLI is not inherently flawed and wont lower your performance, if you meet the minimum standard required. You didn't research what you would need to successfully hold a Crossfire/SLI array and you got burned. Dont turn others way from a legitimate option because you had a bad experience stemming from your own mistakes.
 
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bystander

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Crossfire/SLI does introduce more microstutter than without. Crossfire more so, but crossfire does have a 3rd party tool that with tweaking can get you to better than a single card, at least in the games tested in the link I provided earlier in the post.
 
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Azn Cracker

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Well the i3 shouldn't be the issue because if you pull one card out, you should not be gaining performance. Of course it will be bottle necking you system if the crossfire was working. But I think your problem lies in your motherboard. You only have ONE PCI-e 3.0 16x slot. But when you plug another in, that pcie 3.0 doesnt run at 16x anymore. Most likely it will run at 4x speeds for both slots because your's isn't a high end board. However this should only decrease performance by 10-20% so you still should not be gaining performance when you pull out a card. So my final conclusion is that you are playing games that are not compatible with crossfire. That added with the pci-e bandwidth bottleneck is why you are experiencing bad frame rates in crossfire.
 
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unksol

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Sigh. The i3 is not the bottle neck. His FPS go up with one card. It WOULD be a bottleneck if it worked.

Pulling 80% is fine with no effect on wear, he's below 500W, which would be 70% and your efficiency varys maybe 2% between 20% and 80% on that PSU. Its kinda silly to care about a point, or waste money on a PSU that's way more than needed when what he has is perfectly fine.

Really its a PEBKAC error though. And horrible board. Try the last x16 and you might get SOMETHING. still really horrible setup though
 
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Mousemonkey

Mousemonkey

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How many AAA titles released in the last couple of years haven't supported dual cards whether SLi or Crossfire? I hope for your sake that you come back real soon with an expert answer.
 
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plasmaj12345

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There's no point in getting a 7970 yet unless you plan to upgrade your full system within the next year. The i3 will Bottleneck the 7970. Your CPU should be one of your first priorities. You can sell your i3 and get an i5 3570k. The 7850 could go for $150 on Ebay, and the i3 could go for $115. If you have a Microcenter nearby, you could get the i5 3570k for $180. This would leave you with money leftover to buy a new card. You could then proceed to sell your 1st 7850 and upgrade to a better card like a 7870/7950. Hope this helps
 
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