Whats wrong with my setup??? Help me pls!!

[TheRed]

Hey everyone, I dont know whats going wrong here, I have a z77 mobo, i5k, sdd, hdd, dvd drive and 2 6870s in crossfire all running off this http://www.amazon.co.uk/Antec-Current-Gamer-Power-Supply/dp/tech-data/B004AGTZXI/ref=de_a_smtd

I am getting crashes on the likes of crysis and one card is only registering 150mhz in catalyst when the other is at 300.


first one is:

http://www.amazon.co.uk/XFX-Radeon-HD6870-Graphics-Memory/dp/B0047ZH7GE/ref=sr_1_9?s=computers&ie=UTF8&qid=1348063442&sr=1-9

the other:

http://www.amazon.co.uk/VP-AMD6870-1024A-XFX-Radeon-6870-2xDVI/dp/B005UH9GK8/ref=sr_1_cc_1?s=aps&ie=UTF8&qid=1348063477&sr=1-1-catcorr)

I thought I would need to upgrade the PSU to dual rail but someone said it should work with this PSU once I bought 2 extra molex-to-6pin pcie cable adapters.

But as I said Im getting only a few mins out of crysis and then it crashes.


Whats the best route to take, I can sell me PSU and get another but it needs to be around the same price maybe a little higher...



Please help!

Ian.

 

[Raiddinn]

Does it crash with just 1 video card installed?

 

[TheRed]

No! only when I have both plugged in (with the 6 pin pci cables) once the 'adapted' cables are removed and its only running 1 card with the original 6pin plugs, its fine.

 

[Raiddinn]

Are you sure that both video cards are running at the same settings?

It is generally advised to get the exact same maker of card for that reason, but the cards should be compatible as long as they at least have the same internal settings.

If you haven't made sure both cards have the same internal settings, I would definitely do so.

 

[TheRed]

Well they are both xfx 6870s but one is the DD edition.

Also, how do you mean same internal settings? (p.s. Im pretty new to this sorry)

 

[Raiddinn]

If you go in the ATI Vision Control Panel and go to Information and go to Hardware, you should see something like this towards the bottom:

Core Clock In Mhz 775
Memory Clock in Mhz 1000

I am not sure how this is going to look in a Crossfire configuration, but those numbers (whatever they are for your cards) need to be the same for both cards.

 

[TheRed]

aahahhhhhhh!! thank you Raiddinn, i will try this and let you know what happens!

X)

 

[Rsdevour]

Hi Thered,

I just wanted to let you know that I'm no expert in computers at all but I'm learning little by little. I've been reading the forums for a while now and I've read a couple of postings on this forum talking about bad performance out of the crossfire portion of the graphics. Apparently some people have had good luck with it but others have had horrible expierence with it. Maybe the crossfire could possibly be your problem? Just something that entered my mind when reading your post. That's about as much as I can do to help but hopefully you get the problem fixed.

Good Luck!

 

[Raiddinn]

Crossfire and SLI in general do have their fair share of problems (drawbacks more than benefits in my opinion), but a general problem with CFing in Crysis is a possibility.

 

[Rsdevour]

Crossfire and SLI in general do have their fair share of problems (drawbacks more than benefits in my opinion), but a general problem with CFing in Crysis is a possibility.

Yeah the only thing that made me think of it was when you asked if 1 card worked fine but when 2 are installed then the crash begins. Just my guess but like I said I'm no expert or even close.

 

[Raiddinn]

Indeed that was part of why I asked if it works with just 1 as well.

 

[pauls3743]

Generally, when you Crossfire/SLi graphics cards of the same family but different model they will default to the lower common settings between the cards e.g. if one card has 2GB and the other has 3GB they will both act as if they each have 2GB, equally the clock speeds will default to that of the slower card.

As to your power supply, I would see about getting a power supply which is at least capable of connecting 4off 6-pin PCIe cables, a certified power supply is thoroughly recommended. Using the 4-pin molex to 6-pin PCIe adapters is a recipe for disaster. At most I would use 1, even then I would still be looking to supply each arm of the adapter from a different hard drive feed (not different plugs from the same cable).

The PCIe 6-pin cable is designed to transport 75W of power through 3off +12V supplies and 3off ground returns. This means about 2A on each wire, or a combined total of 6A. Trying to channel this much current through the single +12V wire that the hard drive supply has causes a large voltage drop, the wire was only designed to carry about 4A max. The resultant voltage drop causes fun and games with your graphics cards because you cannot supply it with enough voltage or current.

 

[TheRed]

Thank you so much Pauls, this is both enlightening and heartbreaking. But its good to get some closure on this, Ive been researching it for ages. Would you be able to reccomend a replacement? I am tight on money so I will try to sell the PSU and get a replacement with as little supplemental cash as possible.


orrr...

I could sell the 2 gpus and get a single 2gb card instead? Can someone recommend one?

I am sick of the issues crossfire causes. Especially in Skyrim!!!


Thanks again everyone for all of your help.

Red.

 

[amuffin]

You don't need a replacement PSU.

What you need to do is get rid of both 6870's and opt out for a better single GPU card!

 

[TheRed]

I think you are right, any suggestions? which of the new GTX series would be able to max out all or most games, yet inside my budget of say, €300/$380? AND can be powered without problem by my 620w antec PSU?



R.

 

[TheRed]

Would this be the best for within my budget? its popular on Amazon.co.uk

http://www.amazon.co.uk/Asus-GTX660-TI-DC2OG-2GD5-Borderlands-PCI-Express/dp/B008X36NHA/ref=sr_1_2?s=computers&ie=UTF8&qid=1348129704&sr=1-2

 

[Raiddinn]

All the video cards perform according to their price (minus any special deals).

A card that is $300 is proportionally better than one that is $250 and proportionally worse than $350.

Just find the most expensive one you can afford.

620w will be good enough for any 1x card setup.