2x[r9 280x manual OCed] crossfire, pcie comparison

[ZhyrikaN]

i am planning to OC powercolor 280x's to highest possible clock speeds and crossfire them. in a site, there were fps results of 2x7970 at stock clock speeds on pcie 2.0 x8 vs pcie 2.0 x16 pcie 2.0 x4 vs 3.0 x4 vs 3.0 x8 vs 3.0 x16 and even at 1.0 x16. the results were almost the same, maybe %1-2 difference.
so my question is , am i still going to get nearly max performance (compared to 3.0 x16, max %5 loss) with highly OCed 280x crossfire in pcie 2.0 x16/x16 slots? and what about 2.0 x16/x8 ,, x16/x4 and x8x8?
note: at 1080p.

 

[inzone]

So far graphics cards have not been able to max out the bandwith of a Pci-e 2.0 slot , so if you have the two cards in a 2.0 slot vs. a 3.0 slot you should be getting the same performance. The difference will be in the platform that your using. Regular Intel and AMD processors will provide 16 lanes of Pci-e bandwith on a regular motherboard and so those 16 lanes must be split between the occupied slots. One slot 16 lanes , two slots 8 lanes each. If you get a high end motherboard with a Plex Plex chip addon then you can increase the 16 lanes and get an actual 16 lanes for each slot.

You can also go with the Sandy Bridge-E/ Ivy Bridge-E Platform which those processors have 40 Pci-e lanes of bandwith and that will give you 16 lanes each with some left over , maybe another 8 for a third card.

 

[ZhyrikaN]

So far graphics cards have not been able to max out the bandwith of a Pci-e 2.0 slot , so if you have the two cards in a 2.0 slot vs. a 3.0 slot you should be getting the same performance. The difference will be in the platform that your using. Regular Intel and AMD processors will provide 16 lanes of Pci-e bandwith on a regular motherboard and so those 16 lanes must be split between the occupied slots. One slot 16 lanes , two slots 8 lanes each. If you get a high end motherboard with a Plex Plex chip addon then you can increase the 16 lanes and get an actual 16 lanes for each slot.

You can also go with the Sandy Bridge-E/ Ivy Bridge-E Platform which those processors have 40 Pci-e lanes of bandwith and that will give you 16 lanes each with some left over , maybe another 8 for a third card.

i will be using either i5-4670k or maybe an fx-8350. so is it okay with them? i mean i will pick 8350 since it is cheaper but i was confused because its mobo doesnt support 3.0 pcie.

 

[inzone]

I would go with the i5-4670k and come Black Friday you may be able to get some good deals besides the Intel CPU is a better gaming CPU then the AMD.

 

[ZhyrikaN]

for now , 4670k is better but you know the amazig performance of 8350 on BF4, and we can't know what future will bring can we? i mean 8 vs 4 core is worth taking the risk for me. but btw i still havent get my answer. is it okay 280x OVERCLOCKED( the trick is overclock, maybe stock speed has no performance issue but, what if we OC and 2.0 wont be enough for its high speed?) on 2.0 x16/x8?

 

[inzone]

http://www.tomshardware.com/reviews/gaming-cpu-review-overclock,3106-5.html

You will notice that there are no AMD CPUs at the top level with all those Intel CPUs. The AMD CPUs start at the second level and this is for gaming.

For overclocking with two cards in Crossfire on a 2.0 slot you may or may not get to the limit of that slot and this could be the reason they came out with 3.0 Pci-e even though no single card can saturate a 2.0 slot overclocked or not. I have not heard of a 7990 or 690 overclocked saturating a 2.0 Pci-e slot so it may be ok for this generation of cards and we'll see what comes next.

 

[ZhyrikaN]

i know a single gpu cant reach the limit but i heard crossfire could exceed that limit. is it true?

 

[inzone]

The only possible way it could saturate the slot is with a dual GPU card, don't forget with two cards in crossfire your occupying two slots.

 

[iam2thecrowe]

avoid any 16x/4x pcie layouts for crossfire. always causes issues stuttering/fps dips etc. 8x/8x is good, better if its pcie3 though. dont know why you wouldnt just get an r290 instead of wasing time with crossfire, which doesn't always work properly/sometimes a single card performs better. r290 is more than enough to max out all games on a single 1080p monitor.

 

[ZhyrikaN]

avoid any 16x/4x pcie layouts for crossfire. always causes issues stuttering/fps dips etc. 8x/8x is good, better if its pcie3 though. dont know why you wouldnt just get an r290 instead of wasing time with crossfire, which doesn't always work properly/sometimes a single card performs better. r290 is more than enough to max out all games on a single 1080p monitor.

this is because i am not going to do it right now, maybe after 2-3 years when it seems 1 card is not enugh. ty for your message i will keep it in mind. btw can you recommend me the cheapest motherboard for this build:
-OC 4670k
-OC gpu crossfire r9 280x
-i really dont need anything else, just enough power cores and proper pcie slots. i dont care about the rest, the brand, usb 3.0 count,ssd or anything.

 

[inzone]

http://www.newegg.com/Product/Product.aspx?Item=N82E16813131989

http://www.newegg.com/Product/Product.aspx?Item=N82E16813131975

http://www.newegg.com/Product/Product.aspx?Item=N82E16813131981

The first two are what you should get as they have a lot of features and capabilities , then the third one is the budget one that will give you dual graphics. You have to watch what board you get because the dual video card option only goes down to a certain price after which it's one slot for a video card (x16) and the rest are x4 and x1.

 

[ZhyrikaN]

the first two you have sent are about ~$350 in korea. the third is 200$.
and also asrock z87 extreme 4 is 205$
asus z87-plus 230$ ,,,,,
biostar z87x 3d 192$ ,,,,,,
ga-z87x-ud3h 230$
msi-z87-g45 210$



biostar seems very good for that price. what do you think?

 

[inzone]

For me when it comes to around a $10 or so difference I tend to go for the better component, so in this case that third board I linked would be my choice.

http://www.newegg.com/Product/Product.aspx?Item=N82E16813131981

If not that one then the Asrock Extreme 4.