Ati 4870x2 Crossfired problem with framerates?

[guardiangr]

I think your motherboard was choking your second 4870 X2. If indeed your mobo was running one slot in x16 and the other in x4 consider the following:

PCI-e 2.0 16X = 8GB/s total bandwidth
PCI-e 2.0 8X = 4GB/s total bandwidth
PCI-e 2.0 4X = 2GB/s total bandwidth

HD 4870 X2 = 900mhz (quad piped - 3.6 GB/s data rate)(times 2) = 7.2 GB/s total data rate

Basically, your 2nd X2 was stuck in a slot that couldn't accomodate its bandwidth. If you truely want to do a 4870 X2 CFX you need two x16 slots. Most motherboards will say they have the x16 slots but if you put two x16 cards in you'll run them at x8 each cutting the bandwidth in half.

A 130$ mobo aint going to cut it for you. Going to a 5870 is an interesting step but the single X2 on-par or faster. If you got a 2nd 5870 later make sure you have enough bandwidth, at least an x8 slot to run it properly.

changed the mobo some time now, unfortunately there isn't any for 1156 socket with two x16 lanes on crossfire so my best choice was x8/x8 for crossfire and x16 for single gpu. I also got the 5870 and there is a huge difference now on games, 3dmark etc. At some point i will get a second 5870 so we'll see then what happens

 

[maliclipse]

What games have you seen a positive difference in?

I almost bought a single 5870 when they came out but when I read the all the benchmarks, and boy, did I read all of them, the 4870 X2 was pretty much on par or better FPS wise on most games.

Running a 4870 X2 in a x8 slot would be choking it by a factor of two, two of them would be a complete waste.

Whats your new 3dmark score? My i7-920 @ 3ghz with a stock 4870 X2 gets a hair over 19k. I have another 4870 X2 coming in from ebay next week so we'll see how I scale. My mobo has 3 X16 slots that run 16/16/4 so I'll be golden with no choke points with 2 x X2s.

MH

 

[OvrClkr]

What games have you seen a positive difference in?

I almost bought a single 5870 when they came out but when I read the all the benchmarks, and boy, did I read all of them, the 4870 X2 was pretty much on par or better FPS wise on most games.

Running a 4870 X2 in a x8 slot would be choking it by a factor of two, two of them would be a complete waste.

Whats your new 3dmark score? My i7-920 @ 3ghz with a stock 4870 X2 gets a hair over 19k. I have another 4870 X2 coming in from ebay next week so we'll see how I scale. My mobo has 3 X16 slots that run 16/16/4 so I'll be golden with no choke points with 2 x X2s.

MH

The 5870 is more powerfull than a 4870x2 in most games. Hence the fact it is a single GPU vs. the x2 which is dual GPU.

http://www.guru3d.com/article/radeon-hd-5870-review-test/19

http://www.guru3d.com/article/radeon-hd-5870-review-test/15

http://www.guru3d.com/article/radeon-hd-5870-review-test/16

http://www.guru3d.com/article/radeon-hd-5870-review-test/24

The x2 is a bit faster in DX9 titles but that will soon change once the 5870 gets more mature drivers....

 

[maliclipse]

I disagree, the X2 at this time is more powerful than the 5870 in most games. Guru3d did a good job with the review but many other reviewers had a different experience with the X2/5870. The Guru3d review had the X2 faster in most of the DX10 games but take a peak at these reviews:

http://www.trustedreviews.com/graphics/review/2009/10/06/HIS-Radeon-HD-5870/p5

http://www.xbitlabs.com/articles/video/display/radeon-hd5870_9.html#sect1

http://www.techspot.com/review/198-ati-radeon-hd-5870-review/page5.html

http://www.overclockersclub.com/reviews/sapphire_hd5870/8.htm

These are just a few examples. Games that clearly benefit from CrossFire will do a lot better at this time than the 5870. I agree its a great chip but $ for $ the X2 is better if you have the slot/slots to run it. My original point was that if you're looking to upgrade right now, a 400-450$ 5870 isn't a good deal when you can get a 4870X2 on ebay for 200-250$

I look forward to the 5870s dropping down to about 250-300 and at that point I might consider replacing my X2s with them but then again I'm waiting to see what NVidia does in the spring.

 

[OvrClkr]

I disagree, the X2 at this time is more powerful than the 5870 in most games. Guru3d did a good job with the review but many other reviewers had a different experience with the X2/5870. The Guru3d review had the X2 faster in most of the DX10 games but take a peak at these reviews:

http://www.trustedreviews.com/graphics/review/2009/10/06/HIS-Radeon-HD-5870/p5

http://www.xbitlabs.com/articles/video/display/radeon-hd5870_9.html#sect1

http://www.techspot.com/review/198-ati-radeon-hd-5870-review/page5.html

http://www.overclockersclub.com/reviews/sapphire_hd5870/8.htm

These are just a few examples. Games that clearly benefit from CrossFire will do a lot better at this time than the 5870. I agree its a great chip but $ for $ the X2 is better if you have the slot/slots to run it. My original point was that if you're looking to upgrade right now, a 400-450$ 5870 isn't a good deal when you can get a 4870X2 on ebay for 200-250$

I look forward to the 5870s dropping down to about 250-300 and at that point I might consider replacing my X2s with them but then again I'm waiting to see what NVidia does in the spring.

Well I guess everyone has their own opinions. You gotta be nuts to buy a GPU off of E-bay unless it is a an XFX or Visiontek (with a live warranty). I have had my bad shares with the x2's in the past and at this point in time I would take a 5870 over any 4 series GPU.

The cheapest 4870x2 that E-bay has on sale is a refurbished model at 299.99$. There is a reason it is "refurbished". So I would steer away from such products, specially when they are used. If you want a brand new x2 it will cost you around 375.00/400.00$ <--- :lol:

http://shop.ebay.com/?_from=R40&_trksid=p3907.m38.l1313&_nkw=HD+4870+x2&_sacat=See-All-Categories

Here are a few more benches :

http://www.anandtech.com/video/showdoc.aspx?i=3643&p=17

http://www.anandtech.com/video/showdoc.aspx?i=3643&p=20

http://www.anandtech.com/video/showdoc.aspx?i=3643&p=25