HD4830 Crossfire vs HD4870 1gb

[CAT-THE-FIFTH]

A review here:

http://www.xbitlabs.com/articles/vid...crossfire.html

There is very impressive scaling with the HD4830 in Crossfire!! The HD4870 1gb is beaten in most tests!!

A pair of HD4830 cards will cost you around £170 to £175 whereas an HD4870 1gb costs around £160 to £170.

Peak power consumption for the Crossfired HD4830 cards is higher but idle power consumption is around the same as the HD4870 1gb!

If you use a pair of Sapphire HD4830 cards idle power consumption will be even less as these HD4830 cards down clock the GPU to 160mhz and the video RAM to 250mhz. This is much lower than other HD4830 cards from other manufacturers like the HIS card used in the review!

Also it seems that overclocking an HD4830 card from 575mhz to 755mhz for the core and from 900mhz to 1080mhz for the video RAM only incurs an additional 23 watt penalty. This is useful to know for HD4830 users who want to overclock their cards!!

[arthurleung]

With the HD4870 coming down in price I think it might be a good idea to get dual HD4870 512M.
I'm suprised the core speed went as far down as 160Mhz.

I wonder if that ultra-low clock speed is doable on my HD4870. Although it seems that core speed have no effect on power usage (voltage constant). Underclocking the core to 500Mhz doesn't seems to reduce the power usage by even 1W. Underclocking the memory saved about 20~25W however.

Every graphics card I used in the last 10 years had problem where too slow of a clock speed would BSOD. Haven't tried this HD4870 though.

[sadbuttrue]

I've noticed my 4830 won't return to the power saving 160mhz mode unless I click 'default' in rivatuner. Resetting to the default stock speeds isn't enough. Any changes to the standard clock (overclock or underclock) results in no power saving mode.

When you enable a second monitor the 160mhz mode is disabled, with or without overclock.

The power savings of 160mhz mode vs stock speeds with a single monitor enabled is about 20 watts. I'm skeptical if it will be available in crossfire tho.

[CAT-THE-FIFTH]

You can use ATI Tray Tools to manually adjust 2D and 3D clockspeeds.

Just set the 2D profile to the 160mhz mode and the 3D profile to the overclocked speeds.

I do this for my PowerColor HD4830 and it works a charm!!

However I can only set the lowest clockspeeds to 200mhz for the core and 350mhz for the Ram so it shows that Sapphire card definitely has some changes over normal HD4830 cards. Any lower with the PowerColor card and I get screen corruption. The best thing is that the GPU temperature also dropped a few degrees Celsius too!!