4850 CF issue?

Hiya,

I've got some strange CF issues with two Club3D 4850's here. Each one runs flawless without the other attached but stick em together and nothing works. No matter what I do. Mobo is Asus Evolution with 0401 bios.

Here's what I've tried so far: (on both dirty XPSP3, clean XPSP2 and clean Vista SP1)

- put one 4850 in the top x16 slot: OK
- put the other 4850 in the top x16 slot: OK
- put one 4850 in the bottom x16 slot: OK
- put the other 4850 in the bottom x16 slot: OK
- put both 4850's in blue x16 Crossfire: either no post (out of sync lookalike) or boots and stops when loading windows
- put one 4850 in x16 and the other in x4: both cards are detected and installed, but no CF possible
- been using Catalyst 8.6 with and without hotfix
- tried giving each card its own 6-pin PCIe wiring
- tried with one and two CF connectors

Running out of ideas here.. :shrug:

Weird stuff happening in there.. maybe your PSU is getting ou of juice? Unlikely for a SeaSonic 700W..

Do you have some overclocking going on there? I remember my HD3870s not letting me startup for the first time I installed them. Clocking the system to the default values solved the problem. Then I clocked back to higher values (after installation) and I never had those problems again.

Yeh, usually running 4.5 GHz but tried going down to 3.0 - to no avail

Gonna try a few ideas from BenchZowner now.. :)

Spoken a bit too soon. Yes, the 0501 bios for the Evo was required to make it work.
However CF only works when PEG Port Control forces one x16 to x1.

Setting Full 2.0 x16 and nothing still doesnt work/boot.

Full "true" CF (twin 2.0 x16) only works with all(!) bios settings on auto :(

on an Asus motherboard? that's a shocker. i've owned a few of their motherboards and i loved each and every one of them.

Same here :) cba to wait around for an updated bios tho.. Guess my GX2 will have to do until august

Allrighty then.. I did go ahead and checked what was going on. Started with load setup defaults and took it each single step/change from there.
Turns out the problem is NB voltage - setting anything over 1.41 means either no post, no boot (at all) or lock ups while booting to Windows.

Anything under 1.43v NB and CF runs without probs. Full (double) 2.0 x16.

I've found the issue on both 0201, 0401 and 0501 bios for the Asus Evolution :( ..can someone confirm?

I can't confirm, but I'll have someone at Asus to check it out m8 ;)

That would be cool, thanks bro :)

Issue so far doesn't appear on 0504, still testing..

The power supply falls when BenchMark and Prime95 are executed when setting it
to NB1.43V or more.

The same resulted though all BIOS was tried.

Can you improve it with BIOS?

335*12.5 467*9　420*10
NB1.45V NG
NB1.43V NG
NB1.41V OK

HD4870CF BIOS0115 0201 0504

If you refer to me, then no - gave up getting it to work properly.
So issue is found on 0504 as well.

Interestingly your NB values are exactly similar to mine.

The same resulted though it did still with two Evolution.

P5E3Premium does the same test.
I do not want to think that the problem occurs.

Please forgive me though sentences might be strange because the translation is
used.

Yes, there is such a bug with 48x0 CF.
We're already working on it.

The same phenomenon was able to be confirmed to a regrettable thing
also with P5E3Premium. It was quite the same.
BIOS0504 HD4870CF QX9650

NB1.41 OK
NB1.43 NG
NB1.45 NG

The cause is not understood. Will it be a limit of X48?

To the report for the time being.

The problem did not occur when it was Maximus II Formula.
May I think that it is a bug of X48+HD48X0CF?

Or, may I think that there is a problem on the HD4870 side?

Ah this might be the issue im having. I'll have to reset my mobo to default tonight even though nearly everything is stock and see if that fixes my problem.

Was yours when it was in windows it showed 1 GPU without driver issues and the 2nd GPU had driver issues?

Try the NB voltage by itself first - that might do it :)
(its what was wrong in my and haya's case)

Worth a shot. Mines at default voltage right now, 1.25V or what ever it is so that might help a wee bit. I'll give it a little extra love when I get home later and hope that it fixes it.