Aero on ATI HD 4870 slow as hell

Hello, first sorry for any typo, English isn't my first language.

Aero randomly get realy slow here that i can't watch any videos, the video starts to drop frames, and the interface becomes very slow overall. It is like trying to run it on a ancient GeForce FX5200 or something like that.

After few minutes everything back to normal for some time till it slow down again, with no apparent reason. The problem isn't in the processor since it don't go over 10% of usage during video play, I am not using avivo here, or other uses.

The only way i found so far is to disable and enable aero in the personalize menu. This bring back the speed to normal.

I am runing a dual monitor setup, one in the HD 4870 (primary) and the other on the onbord HD 3300 video.

Tried the catalyst 9.10 and 9.9 video drives and the problem persist.
Any idea?
Thanks in advance.

Check the settings and make sure hardware acceleration is on.

What settings?
In dxdiag everything is ok. Games play fine too. The only problems is when aero is enabled.

If I may ask,

I am runing a dual monitor setup, one in the HD 4870 (primary) and the other on the onbord HD 3300 video.

why? Your 4870 is more than capable of running dual monitors, that and with the onboard enabled you are taking away from system ram. Disable the onboard, and connect the second monitor/display to the 4870, then once back in Windows go into your display properties and set it to "extended", that will allow bother monitors to show different things (clone mode is both showing the same thing).

stormy13 both are d-sub monitors. and the image quality is bad with 2 in the HD4870 (not good ramdac i think), using dvi-dsub adpters. The memory usage on the secondary is not a problem, i only let the sideport enable so no main memory use.

I just removed the plug-ins to enable aero effects on firefox, the one of the tutorial in this forum, and things seems back to normal. Since after 2h without firefox open the problem didn't come back i was thinking that it may be the cause...

The problem is back again .

I've seen some people with similar problems, and many of them is using dual monitors. ATI fault perhaps?

Probably not. Been running dual monitors off my 4830 (one connected DVI and the other VGA, and both LCD) for months and never seen a slowdown like you are talking about in either 7 or Vista.

Tried the catalyst 9.10

Unless you are using the beta that surfaced a week or so ago, the 9.10 isn't out yet.

stormy13, vista works fine here too. only in 7 i have this issue.

Unless you are using the beta that surfaced a week or so ago, the 9.10 isn't out yet.

Yep, the 9.10 beta.

What driver version are you using there? I tried 9.8 too, the problem still persist.

9.9 at the moment. Also haven't done any "tweaking" to anything video/Aero related; didn't see any point as everything is working as it should.

What are the rest of your system specs, and are all drivers installed and updated (and not updated through Windows Update)?

OS 7 x64 RC 7100
CPU Phenom II x4 810
Motherboard M4A78T-E
Memory 4x2GB OCZ Platinum 1600MHz
Graphics Card ATI HD 4870
Sound Card Onbord
Monitor(s) Displays primary 1920x1080 secondary 1280x1024

All drivers are the mostly recent, except video.