Overclocking a HD3870

Bah Bah Bump

just google it mate. They do overclock rather nicely from what I've read.

I'll tell you my experience overclocking the 3870. 3870@stock speeds using e6400@2.9, 2gb ram on a MSI P965 Platinum motherboard. I scored 10,500 in 3dmark06. I bumped the speeds up to 825/1220 and scored 11,022. After that, I bumped the speed to 850/1275 and scored 11,055. I probably won't try to push anything further as I am happy with that score. I feel as I am CPU limited anyway.

Here is a 3870OC benchmark that shows how your performance might scale:
From DriverHeaven review which also covers CrossFire support)

I have not experienced any lock ups. Right now I have my clock set at 840/1291. No problems anywhere including gaming and benchmarking. If I were you, the furthest I would go would be an 850 core. It will lock up at anything past 862 core speed anyway unless you flash your bios (not worth it).

You think your CPU limited. I have a Pentium 4 3.0G 630, 2G pc-5400 running a 3870.

I am taking baby steps with OCing my Sapphire 3870, i am at 805 core and 1200 mem. I tried it at 825 and it blacked out after a few minutes. At 825 core, it was close to 85 degrees c at load. At 800, i am at 75c at load.

With 2xAA, 2AS and most of the eye candy, i am getting 60+FPS. for COD4. Usually higher. Until i upgrade my mobo and CPU, higher settings really drop my performance.

EDIT: i had my CCC controlling all the settings, set to quality. i was getting real low FPS. When i set it all to app controlled and let the game handle it, it ran a hell of a lot better.

yeah, when i set CCC to permormance my FPS dropped to 20-40. What i did was use custom settings and set all the 3d settings to "application controlled". I started getting 50-70FPS with COD4 on medium settings, 2xAA, 2xAS at 1024x768. That is about where it should be. In Tom's article "AMD Radeon HD 3800: ATI Strikes Back" http://www.tomshardware.com/2007/1 [...] age17.html the 3870 on COD4 was getting slightly lower at higher res.

anything i try over 800/1200 locks up.

Another thing: i had COD4 playing at some custom settings getting 50-70FPS. I reset COD4 to optimal settings. Now i am getting 70-90 FPS. 4xAA, 4xAS, 1024x768.

Bottom line: CCC 3d settings to application controlled, ATI Overdrive 800/1200, I am happy now. If i get a new cpu and VGA cooler i might try more later. one thing i forgot to mention, my board is PCIe x16 not 2.0.

Wow how did u get that cool temps? My idle is around 45-50 while load it gets to 70

Gigabyte sell a 3850 with this cooler already on and in the couple of reviews I have seen nobody has had load temps as low as that. Have you had riva tuner or Ati tool logging those temps or have you just come out of a 3d application and then checked them? If possible post some screen shots. I'm not calling you a liar or anything I'm just a bit pessimistic about those values. I'm looking to buy a 3870 in the future so I would be interested to find out.

Edit: Could you also post a screenshot of GPUZ because that is one hell of an overclock.

i run mine @ 850/1300 with no probs, theres a bug in the bios to stop u goin over 860 if u read on the web

Cheers detpower

That is a good overclock considering its not meant to be able to go over 860 without the bios update. Those temps are very impressive. They are much closer to what I was expecting. I just thought only a 9c increase under load was asking a bit much. When I do get a 3870 you have given me a target to aim for.