Problems with six cores being slower than same clock speed quad core.

[jstrob]

Hi,

I already started talking about that in the bechmark thread
http://www.chaosgroup.com/forums/vbu...y-RC3-required)

But I will continue here. I just swapped my cpu for supposedly faster one (and undoubfully more expensive!) But I am really deceived since they render slower in vray. I haven't have time to test anything else with them though.

My MB is Asus Z8NA-D6 and my cpus were dual xeon nehalem quad cores E5520 (2.26Ghz) swapped in the same machine for dual xeon six cores Westmere (also 2.26Ghz). But they render slower (benchmark scene rendered in 59s for the quad cores and 1m 6.0s for the six cores.

Alos if I use the application CPU-Z it reads my core speed at 1600.2 Mhz... even if I am rendering CPU-Z gives me the same core speed.

Someone suggested I reset my bios, I will have to try that. (I flashed it before the swap cause the old bios did not recognize 5600 series CPUs).

Anyway. I just hope I was not sold fake cpu... I bought them at a reputable store.

[vlado]

It would be best to test with a scene that takes more than a minute; a difference of a few seconds is not indicative of anything in particular.

Best regards,
Vlado

[ghiom3d]

Hi,



Alos if I use the application CPU-Z it reads my core speed at 1600.2 Mhz... even if I am rendering CPU-Z gives me the same core speed.

It's look like a Bios Issue.
You have updated your bios, but i think that the problem is the new bios have difficultys to identify the CPU frequence and Multiplier.
I would advice you to setup your CPU manually in your Bios.
I always do this since the Cpus now are working automaticly in different speed ( boost, energy saver .. )

[tricky]

Couldn't this be to do with RAM assignment to different cores?
Are you using DDR3 in triple slot configurations?

[jujubee]

This is a pretty important question too - are you certain your motherboard supports the new hexacores? Sometimes manufacturers release new BIOS to support newer chips. Other times you're out of luck unless you buy a new motherboard.

[jstrob]

thanks all I found the solution and yes it had to do with the bios. All I did was to reset the bios to default settings. Then CPU-Z show me the right core speed and the benchmark scene is now rendering at 41.7s! So now that's faster than the quad cores!!! I will also try to render another benchmark scene if I have time soon.

[jujubee]

lol - I get a cookie right?
As Vlado said before, you're probably best off running tests on a more complicated scene that takes longer to render as this one is getting rather old.

[jstrob]

Yes thank you Jujubee, you found it right away! I'll try to find time to render a cookie for you Since I just flashed the bios I didn't think about reseting it at first but I still had to do it (it was a soft reset in the bios settings, not a hardware reset by using jumpers).

[jujubee]

lol. I just know from having made that mistake before and beating my head against a wall... Same thing also happens to newly added RAM. If you want, you can send me one of those processors instead.