It is quite strange statement.

First thing is not to make strange downgrade to B75.

Issue here can be either in used H264 decoder (I mean software) or storage.

Most probable cause for this is that you did not removed old drivers and may be some sother software settings remained.

well, I formated the hd and reinstaled everything again, so it is a new install each motherboard changes.

I downgraded from Asrock Z77 to Asus B75 because it was a cheap attempt and another manufacturer and another chipset, but no solution...

I removed the Gpu and used the onboard gpu, no solution...

all other hardware is the same, just changed motherboard and cpu... this is why I am thinking there is an issue with ivy bridge platform.

It freezes in H264 or in cineform all-i avi files also.

Could it be a problem with incompatible memory? You have upgraded the board but not the memory.

@tinbeo

He tested with GPU that is inside CPU :-)

about memory I don't believe because ivy bridge is compatible with 1333mhz memory which I own. and everything in computer is stable, just video playback is freezing. But who knows?

Problem now is: no money to buy anything! I am considering to sell cpu and motherboard and do a downgrade to 2500k and p8p67 asus. but who knows it will work?

what I know is the Q8400 and asus P5P43TD was working flawless.

Maybe there is some software / driver issue not compatible with the ivy bridge architecture in windows 7?

check memory is a good idea, but would need to borrow, not buy. or find a store which are willing to test for me before buy and to pay in 12x small monthly payments...

@Vitaliy_Kiselev

Thanks. This is the way to go. A small shop to do tests before buy anything. And when it works keep it untouched for years.

@driftwood

I will do the memory test first, memtest is running, will do memtest86+ also

@apefos Make sure you do as Asus suggest when retrying both 4Gb DIMMs (8gb memory). Install into slot A2 and B2 for max compatibility in Dual Channel mode.

what brand and watt is your powersupply?

@endotoxic

Video freezing due power supply is not common issue :-)

As for "video playback consume all resources" is is absolutely not true. Even in full software mode (that was not the case) such processor use very little resources for playback.

Before you do anything else, try completely removing all traces of the video driver and using one that is say from October 2011. Newer drivers are very often not compatible with HD video as they are only tested on on a small number of recently made cards. If possible, use the driver that came with the graphics card. For example, both of my GT 240s are great graphics cards, but they don't work with the latest drivers.

I am using the same driver I used in previous working system, 301.42 nvidia, It was stable in old system.

My PSU is 600w 80% guarantee C3Tech brand. I did some calculations in the online outervision and it is ok.

No overclock. I don't do game.

Maybe the problem is not in some piece of hardware, but maybe the combination of them, one piece of hardware is not doing ok with other. maybe this memory in the q8400 system was ok but no good in the new system.

Since the playback is working until now with just one memory module set to 1333mhz on bios I am starting to believe a better memory can solve the problem. I am using cheap generic 1333mhz 2x4gb memory.

I can try memory timings and power, but it seems these two modules are not doing good in dual channel.

I will keep one 4gb module for now. I will do one hour playback with all videos in same timeline in full resolution. after that will start editing the new video. If one module works, I will keep this configuration until get money to buy other memory or buy in 12x monthly payments or sell one motherboard to do it. but before sell one motherboard I will install the Asrock and try it with just one module also. 18 minutes playback until now and one module is working.