Crossfire Query

[MatTheCat]

I currently have a Sapphire HD 4870 512MB and feel that I would like a little more graphical power.

Not being convinced that there is going to be any pressing need to rush out and buy a DX11 card for at least another year or maybe even longer, I quite like the idea of drastically increasing my GPU power on the (relative cheap) by Crossfiring my current card with another ATI 4*** series card. From the Benchmarks I have seen a crossfired 4870 pair beats a 5870 (narrowly), albeit without any DX11 features.

Bearing in mind I know nothing about Crossfiring (I do have a X38 board 16x + 16x PCIe though), which of the following combinations make most sense in crossfire:

4870 512MB + 4870 512MB
4870 512MB + 4870 1GB
4870 512MB + 4890 1GB

Thanks to any of you knowledgable geeks in advance.

[zithe]

The other 512. Anything above another 4870 512mb won't give you any added benefit. The 512mb 4870 will limit any faster card.

[oily_17]

Originally Posted by MatTheCat

I quite like the idea of drastically increasing my GPU power

I am not sure about drastically increasing your GPU power.

But I have two of those cards in the wife's rig, if you want to compare some benchmarks I am willing to run some tests with them crossfired.

You can then decide if it is worth the extra cost.

[FreedomEclipse]

depends if you really really need the extra performance, at this stage - the price you pay for another 4870 wont be worth it unless its really really really stupidly cheap & retailers that do have what little stock left will still sell as close to the £100 mark as possible unless you buy secondhand or from ebay, so it all depends what you really need it for (I have 2 4870 toxics which should get me to the end of the year & possibly further) next thing id probably try to do is overclock your E8400 to 4Ghz at least, that will add some more frames & try n hold out as long as possible.

as for 2 4870's beating a 5870 id like to hear where you got that from as all the info ive read says its not possible. & if you got it from Tomshardware, then you should know better then to trust them

---

anymore questions about crossfire just ask. I might not know a lot but I am running the configuration you're thinking about running

[FreedomEclipse]

throwing up a few benchmarks since I already had them done for the vantage & 3DM06 threads.....





so bench your rig & compare, If you think its worth upgrading then more power to you i say.

[MatTheCat]

Originally Posted by FreedomEclipse

throwing up a few benchmarks since I already had them done for the vantage & 3DM06 threads.....

http://i113.photobucket.com/albums/n...ntageFinal.jpg

http://i113.photobucket.com/albums/n...pse/3d06-1.jpg

so bench your rig & compare, If you think its worth upgrading then more power to you i say.

Hmm..

These benchs don't quite correspond to the near doubling of frame-rates that I am seeing in the various benchmarks across the internet. Good to know what the real deal is! I would thank you twice if I could!

[FreedomEclipse]

Originally Posted by MatTheCat

Hmm..

These benchs don't quite correspond to the near doubling of frame-rates that I am seeing in the various benchmarks across the internet. Good to know what the real deal is! I would thank you twice if I could!

lol, Crossfire will never give you double the performance - its just not how it works.

[oily_17]

Got to agree with Freedom, you will never see double the FPS with crossfire over a single card.

I have run bench's before on these two cards and just you dont get it..I dont have the figures to hand but it wont double the FPS

[MatTheCat]

Originally Posted by oily_17

Got to agree with Freedom, you will never see double the FPS with crossfire over a single card.

I have run bench's before on these two cards and just you dont get it..I dont have the figures to hand but it wont double the FPS

I take all your words for it but there are plenty benchmarks around that suggest that a 4870X2 (same as 4870 CF?) is performing at around 40% faster than a single 4870.

Here is just one example of many:

http://www.xbitlabs.com/articles/vid...0_7.html#sect0

Would it be the case that all these benchmark reviews have got it wrong?

[MickNat]

It wont double his FPS but it will give him a nice boost in games, just look at 2 512mb HD 4850's in crossfire, there no slouch and the 4870's are so cheap at the moment, you would be hard pressed to find better performance for the money

[erocker]

You won't get double FPS in Futuremark benchmarks. They arent very good for determining CrossFire. In many, many games you will get close to double the performance. With a 512mb card though, the memory bandwith may be a bottleneck.

[FreedomEclipse]

at most you will probably see upto 30% more performance & if your real lucky maybe 35-40%% but thats only if you overclock the tits off the cards - trust me I know, each of my 4870's have been RMA'd at least once in less then a year of ownership

[MickNat]

Originally Posted by FreedomEclipse

at most you will probably see upto 30% more performance & if your real lucky maybe 35-40%% but thats only if you overclock the tits off the cards - trust me I know, each of my 4870's have been RMA'd at least once in less then a year of ownership

I disagree, most games scale very well with crossfire and sli nowadays, and some show upto 80%+, its a good upgrade to go crossfire being as his 512mb wont fecth that much so if he can get another for fairly cheap (look around and you could find one for around £80 imo) it will perform better than any single card for the same money.

[oily_17]

Originally Posted by erocker

With a 512mb card though, the memory bandwith may be a bottleneck.

This will be a big factor for your gaming needs.You can buy a cheap 4870 now or just save for a newer card with more memory.

[MickNat]

Originally Posted by oily_17

This will be a big factor for your gaming needs.You can buy a cheap 4870 now or just save for a newer card with more memory.

His resolution is only 1680x1050 512mb is fine for most games at that res except GTA4 and Crysis

[Loosenut]

Wow, I never thought they were going for this much

http://cgi.ebay.ca/Diamond-Multimedi...item20afecd704

[MatTheCat]

Originally Posted by MickNat

I disagree, most games scale very well with crossfire and sli nowadays, and some show upto 80%+, its a good upgrade to go crossfire being as his 512mb wont fecth that much so if he can get another for fairly cheap (look around and you could find one for around £80 imo) it will perform better than any single card for the same money.

Yeah...I think I have just sourced a 512MB 4870 for £60. Comparing this with £230 for an HD5850 (another viable option), there is only one sensible choice here really! Although many here disagree, all the benchmarks around the internet indicate that i will get better performance with a 4870 CF than I would with HD5850 and in some cases also the HD5870...(minus DX11 of course).

[MatTheCat]

Originally Posted by zithe

The other 512. Anything above another 4870 512mb won't give you any added benefit. The 512mb 4870 will limit any faster card.

In an ancient post, another forum member explained to me that this 'card limiting' factor only applied to SLI. With CF however he stated that the fasted one will be fully used first and the second ones performance would meet somewhere in between...

...or something like that.