Finding it really hard to make up your mind....

Things change I've changed · 25 Jun 2008 at 15:44

I am,

I'm finding it really hard to decide what to do this time round, no doubt I'm not the only one, what with the various different PCI-E configurations on the market today, PCI-E 1.0/a, 1.1, 2.0, 4x 8x x16, oh and I only recently found out that PCI-E 2.0 is double the bandwidth of 1.0a/1.1 (thanks greebo), I can see how some people including myself can get a little bit confused, also now that crossfire has become an affordable incentive for the masses it definitely does mix things up a little, you may need a new motherboard, you may need a new power supply, so a cheap CF setup could end up costing you a bundle.

If your a noobie I would definitely read up on this article in regards to the different PCI-E configurations, helped me out allot,

http://en.wikipedia.org/wiki/PCIe

It seems that not many people should have an issue running an ati 4850/70 on any PCI-E 1.0a/1.1 capable motherboard but you may be constraining the peak performance of the card due to the limited bandwidth of PCI-E 1.0a/1.1, 16x speed on a PCI-E 1.0a/1.1 slot is half the bandwidth of 16x speed on a PCI-E 2.0 slot, so contemplating a crossfire setup on a PCI-E 1.0a/1.1 motherboard would seem to be a bad idea, no manufactures seem to go out of their way to explain this so no doubt you well get people purchasing crossfire setups for their ageing motherboards that like mine that states it is crossfire compatible but will only run the cards @ PCI-E 1.0a 8x8x and will be largely losing out on the full potential of what these cards are capable of.

Anyway I thought I post this just in case anyone out there was a little confused and also the answers I get to the following questions may help other people also,

A few Q's if anyone would be so kind,

1) To run 2 x ati 4850/70's in crossfire do you need a link to join the cards together ?, and if so where do you get them from ?

2) It would appear that the ati 4870's require 2x6pin power connectors, now running these in CF would obviously mean that you would need 4x6pin connectors available, what PSU is recommend to do the job in terms of available connectors and minimum wattage ?

3) Do you get any 2x6pin adaptors in the box and if so how many molex connectors do they use ?

4) Am I right in thinking that the best motherboards to purchase for a CF setup are those with a x38/x48 chipset as they can run 2 x ati 4850/70's at a full PCI-E 2.0 16x speed ?

reflux · 25 Jun 2008 at 15:52

lowrider007 said:
1) To run 2 x ati 4850/70's in crossfire do you need a link to join the cards together ?, and if so where do you get them from ?

Yes. Unlike SLi though, the bridge comes with a graphics card instead of the motherboard. All the cards have two 'fingers' for CF but apparently you only need to connect one if you're running two cards, but I put both on when I was running 2xHD3870s because it looked cooler.

lowrider007 said:
4) Am I right in thinking that the best motherboards to purchase for a CF setup are those with a x38/x48 chipset as they can run 2 x ati 4850/70's at a full PCI-E 2.0 16x speed ?

Yes.

Things change I've changed · 25 Jun 2008 at 16:43

Any help on questions 2/3 ?,

what PSU's out there come with 4x6pin connectors ?,

would this ?

http://www.overclockers.co.uk/showproduct.php?prodid=CA-030-EN&tool=3

Wilst · 25 Jun 2008 at 19:31

I beleive the 4850 has just a sinlge 6-pin connector not sure about 4870 though. This pic shows the connector quite clearly http://www.overclockers.co.uk/showp...3 TV-Out/Dual DVI/HDMI (PCI-Express) - Retail

Devious · 25 Jun 2008 at 19:55

4850 1x 6pin

4870 2x 6pin

pieman109 · 25 Jun 2008 at 20:09

4850 has one 6 pin connector. I've already got a gigabyte X38 DS5 mobo, and a corsair 620w psu with 2 x 6 pin connectors. I've also ordered 2 x 4850 which should be arriving tomoz hopefully. Gonna try them in Xfire when I get the time (luckily I'm off tomoz as well). I didn't go for the 4870 as want to have a go at xfire, apparently the results sre encouraging. If it turns out to be a bit of a failure, I'll flog one and keep the other.
I'll post back later tomoz with any results, if any.

Devious · 25 Jun 2008 at 20:12

pieman109 said:
4850 has one 6 pin connector. I've already got a gigabyte X38 DS5 mobo, and a corsair 620w psu with 2 x 6 pin connectors. I've also ordered 2 x 4850 which should be arriving tomoz hopefully. Gonna try them in Xfire when I get the time (luckily I'm off tomoz as well). I didn't go for the 4870 as want to have a go at xfire, apparently the results sre encouraging. If it turns out to be a bit of a failure, I'll flog one and keep the other.
I'll post back later tomoz with any results, if any.

The different between 2 x 4850 and 2x 4870 doesnt look very big upto 1920x1200. Im very temped in 2 x 4850 but im trying to source a x48 mobo that doesnt cost the earth.

Ill be interested in what you think of them

fornowagain · 25 Jun 2008 at 20:20

lowrider007 said:
1) To run 2 x ati 4850/70's in crossfire do you need a link to join the cards together ?, and if so where do you get them from ?
One bridge comes with each card, only one is needed for crossfire, two for crossfireX
2) It would appear that the ati 4850/70's require 2x6pin power connectors, now running these in CF would obviously mean that you would need 4x6pin connectors available, what PSU is recommend to do the job in terms of available connectors and minimum wattage ?
I would look at a solid 600W/50A(12v) unit, maybe the Corsair range.
3) Do you get any 2x6pin adaptors in the box and if so how many molex connectors do they use ?
Probably yes from the reviews I've seen, and 2x molex = 1x 6 pin
4) Am I right in thinking that the best motherboards to purchase for a CF setup are those with a x38/x48 chipset as they can run 2 x ati 4850/70's at a full PCI-E 2.0 16x speed ?
That's right either one, P45 potentially has the same peak bandwidth issues in some applications.

Rob-- · 25 Jun 2008 at 20:20

i was thinking of the same questions in my head

Tooks · 25 Jun 2008 at 23:08

lowrider007 said:
I am,

3) Do you get any 2x6pin adaptors in the box and if so how many molex connectors do they use ?

The 4850's only need one 6 pin PCI-E connector, the 4870's need two. Don't know about other brands, but my Sapphire 4850 model came with a molex to 6 pin PCI-E connector, and that only needs to connect to one Molex connector.

pieman109 · 25 Jun 2008 at 23:47

Devious said:
The different between 2 x 4850 and 2x 4870 doesnt look very big upto 1920x1200. Im very temped in 2 x 4850 but im trying to source a x48 mobo that doesnt cost the earth.

Ill be interested in what you think of them

I'll let you know tomorrow hopefully. I honestly believe that if ppl want that little extra performance over a 4870, 4850 in Xfire is the way to go providing they have a suitable mobo. I know it costs a bit more (in my case about £40 ish), but from what I've seen and read, I reckon its worth it. Others might not but I want to give it go. I'll be interested to see what the comparisons are between two 4850 and a single 4870 are.

Things change I've changed · 26 Jun 2008 at 00:23

thanks very much guys, I didn't know that the 4850 was only 1x6pin, thats pretty awesome, makes it even more of an incentive to CF those baby's, I've been looking at the bench marks and I really don't think 2x4870's is worth it over 2x4850's, plus going with the CF 4850's I wouldn't need to buy a new PSU.

pieman109 · 26 Jun 2008 at 00:27

lowrider007 said:
thanks very much guys, I didn't know that the 4850 was only 1x6pin, thats pretty awesome, makes it even more of an incentive to CF those baby's, I've been looking at the bench marks and I really don't think 2x4870's is worth it over 2x4850's, plus going with the CF 4850's I wouldn't need to buy a new PSU.

Cheaper as well but you do need a suitable mobo, X38/X48

Things change I've changed · 26 Jun 2008 at 00:35

pieman109 said:
Cheaper as well but you do need a suitable mobo, X38/X48

I'm gonna get an asus X38 board, it almost pays for it's self going with the 4850's instead of the 4870's and at the same time I may be able to push my ickle E6300 past the 3gig mark, my current mobo is awful at overclocking as it's a genuine Intel board so it has very limited overclocking options in the bios.

pieman109 · 26 Jun 2008 at 00:45

lowrider007 said:
I'm gonna get an asus X38 board, it almost pays for it's self going with the 4850's instead of the 4870's and at the same time I may be able to push my ickle E6300 past the 3gig mark, my current mobo is awful at overclocking as it's a genuine Intel board so it has very limited overclocking options in the bios.

The gigabyte version is well stable and not too shabby wrt overclocking either.

Vertigo · 26 Jun 2008 at 07:40

Here's another question. How much would a 4870x2 be constrained by the bandwidth of a PCI-e 1.1 16x slot on a P35 mobo compared to PCI-e 2.0?

Not upgrading my motherboard and replacing my OS this close to Nehalem basically.

BubbySoup · 26 Jun 2008 at 10:23

lowrider007 said:
Any help on questions 2/3 ?,

what PSU's out there come with 4x6pin connectors ?,

would this ?

http://www.overclockers.co.uk/showproduct.php?prodid=CA-030-EN&tool=3

This PSU comes with 4x6 pin and is rather wonderful, if slightly overkill. A 4870 Crossfire rig pulls around 450w or so at load, meaning the fan on this PSU never spins up past it's default very, very quiet setting.

http://www.overclockers.co.uk/showp...2.2 Modular SLI Compliant PSU (CMPSU-1000HXUK)

Steedie · 26 Jun 2008 at 10:32

Vertigo1 said:
Here's another question. How much would a 4870x2 be constrained by the bandwidth of a PCI-e 1.1 16x slot on a P35 mobo compared to PCI-e 2.0?

Not upgrading my motherboard and replacing my OS this close to Nehalem basically.

I'd like to know this also

Greebo · 26 Jun 2008 at 11:00

Steedie said:
I'd like to know this also

I would guess quite a bit but nobody will know for sure until they are out.