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strange problems with Crossfire HD5850 setup

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Joined
27 Aug 2011
Posts
11
I'm having strange problems with my crossfire setup of 5850's, and was hoping someone could shed some light onto just what is going on with them and how to fix them.

The main issue i am having is that in a game regardless of how high fps the game is running it feels like it is chugging along at 10-15fps.
Fraps could say the game is 120fps but it still feels low and unplayable.
It does this at complete random, i have tried checking and unchecking every imaginable setting in the CCC, sometimes the game would suddenly become playable, but after a reboot it would run terrible again even with the settings that previously worked.

I've tried locking the clocks high by registry tweak + bios edit, updating to the latest drivers and used driver cleaner but the problem persists.

My display drivers also crash pretty often and then windows recovers them. Or when booting up my pc it has suddenly decided one of my two monitors will now run at a terrible resolution so i have to go into CCC and disable the monitor, then re-detect it for it to work again. That usually works except lastnight trying to detect again would crash the drivers again. Did this 5 times untill my screen was nothing but a bunch of garbage.

Both cards run fine on their own, its in crossfire they seem to hate each other.

The rest of my system is: Core I5 @ 3.6Ghz. 12GB ram, 2TB Raid0 Hdd configuration, Asus P7P55 LX Mobo, 600w PSU.

Does anybody have any idea how i can fix this? Thanks.
 
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Temps stay in 50-70c range depending if i've overclocked or not.
I have overclocked them before a bit but i run them on stock all the time at the moment.
 
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Have both cards run together properly before or are the problems only since you got the second card?

750W PSU, what make and model?

The second PCI-E x16 slot only operates at x4 speed. This shouldn't have too much of an effect but possibly it is.
 
They have worked together in crossfire mode before fine in the past, but then i updated my drivers and they havnt worked the same since. I first noticed something was up after updating that when i moved windows around my sceen would do this weird flickering effect. I found that was caused by the clocks jumping up and down quickly when monitoring in gpu-z, it didnt do that before updating. Locking the clocks with a bios edit solved that problem but not this other one.
I've reformatted my computer too and the problem remains.

ah i thought i had a bigger psu, It's actually a 600w, OCZ 600W StealthXStream. Though it is kinda old, 4 years old
 
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PSU is a bit marginal for Crossfired HD 5850's and likely it's been running at quite a high load percentage when you've been gaming.

High load for long periods is not good for a PSU and they also deteriorate with age and use.

Do you have any friends or family with a PC you could use to test the cards out?

Preferably someone with a beefier PSU.
 
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How high would you consider too high of a load percentage? and would that be wattage or just the use of rails and such?

I have ran this psu practically all day for the past 4 years so maybe it is getting a bit worn out. Also this psu has only 2 PCI-E connectors, i'm using adapters for molex to PCI-E for the other gpu, would that have an effect?

I don't have anyone else i can get to test these cards that has a bigger PSU, though speaking of which i just tested each card in each slot. Each runs fine on their own, and the difference in fps between the 4x and the 16x slot is 20%, atleast in deus ex human revolution, if anyone is woundering
 
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what else is your psu powering

i found crossfired 5850's with an Phenom II 955 and 3 HDD's to be the limit for my Corsair TX650W, it would boot wih 2 HDD's but not the third :)
 
In total it's powering:
2 120mm case fans
cpu fan
dvd-rw drive
pci usb hub (nothing connected to it though)
x-fi sound card
2 1tb hard drives
i5 processor overclocked
2 5850's
4 sticks of ram (2x2gb 2x4gb)
My usb devices are powered by a hub they're connected to.
 
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My Antec Truepower 650w handles my CF 5850s ok

Spec:

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2 x 2GB DDR2 1066
Sata DVD RW
2 x 1TB HDD
2 x 500GB HDD
X-Fi Music
2 x 140mm Fans
5 x 120mm Fans
H50
Logi G15 Keyboard
Logi G5 Mouse
 
To be on the safe side I would recommend a decent branded (Antec,Corsair etc) 750w.
 
Which one of these would you recommend?
Coolermaster GX 750W PSU
Antec TruePower 750W Modular PSU

I'm thinking the antec one but dont want to spend too much.
 
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You have got yourself a very good and very quiet PSU there.
Welcome to the Antec owners club lol

Sorry for the blatant fanboyism!
 
Edit: Problem seems to be nearly fixed with the new PSU. Thanks :)
Games are running much much better now, and getting fps boosts in crossfire mode, albiet not much but its still a boost (im guessing because of the 4x slot?)
But something seems a bit odd. It only works right when i have one monitor on.
If i enable the 2nd monitor all games will run terrible, Even in eyefinity mode it runs terrible. The only way the game runs smooth is if my 2nd monitor is completely disabled, any thoughts how to fix this? Thanks
 
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