Hi guys,
I just bought the ATI HD 4850. First off, a lot of people seem to have issues with overheating and thats because the fan barely runs on the card. I was shocked at the 81 C idle temp i was getting, then i found the workaround here: http://forums.guru3d.com/showthread.php?p=2751569 . Im pretty happy that i dont have to get an after-market cooler to overclock. However, i only have a 500W power supply. It's an OCZ Stealthstream with two 12V rails @ 18A each. My specs are: Athlon X2 5200+, 2x1GB PC6400 Ballistix, SB X-FI Extreme Audio, not sure on the HD, nothing fancy though, 2x120mm fans, 1x80mm fan. I was wondering if i overclocked maybe 8-10% past the 625MHz 993MHz stock speeds if I would see crashes, BSODs, etc, solely based on any inadequacy from the power supply. In other words, do i need a better power supply to OC my HD 4850?

No I have a 520W Kingwin and I have my HD4850 to 700/1100 and I have no problems. The rest of my system is overclocked as well.

1Haplo

You won't need a new power supply to OC your gfx card, plus it's not worth upgrading your PSU just to get that 2-3 Fps more.

I've had two 3870's & a 6000+ running on 580w. Enough power to overclock either the CPU and GPU's, but not at the same time...

The most the card can draw is the maximum power supplied by the motherboard and the additional connector, so if your PSU has a 6-pin PCI-E connector it should handle a full load on that connector(I believe it is 75W from a motherboard and 75W per 6-pin adapter for power).

great, thanks for all the replies. now i'll find out what this puppy is really capable of. this is definitely the best card in terms of price/performance since the 8800GT. ati definitely wins this round. I wonder if Nvidia can rebound , they seem to be pretty far behind in both fab process and memory bus type...

Not memory bus type, nVidia currently has wider memory buses, the GTX280 has 512-bit, where as the HD 4870 has 256-bit. They are behind on memory type though, GDDR3 Vs. GDDR5, but they use the wider bus to make up for slower memory.

As far as fab process, the 9800GTX+ is coming out soon and is at the same 55nm fab process as ATI has been using.

Thanks for that link! Best part of your post, IMO...

As to your question, will OC'ing add stress to your PSU? Of course it will. But in your case, probably not enough to worry about.

No problem. Ive gone through too many forum topics posted about the 4850 with people complaining about the heat issue. I figured if I was going to start my own topic, I should at least include that very useful piece of information so im glad it helped at least one person.

As for the 9800GTX+ , unless Nvidia can set a competitive price on that card, ATI's 4800 series still wins. Plus the the 4850 is single slot which is a big plus for people like me who dont have giant towers or sli boards. For once, Nvidia is doing the catching up.

The 9800GTX+ is going to be $200 MSRP, as that is what you can get it for direct from EVGA's website. That is the same price as the HD 4850, so it looks like those cards will trade blows at the same price range. The heat issue with the HD 4850 bothered me because none of the ATI manufacturers seem to support aftermarket coolers, and I already have a good one(Zalman VF-900), so for people like me who want to add our own cooling EVGA and BFG seem to be the only two companies that support them under warranty.

ATI's 4800 series is pretty impressive, but this isn't the first time nVidia is playing catch-up with ATI, the GeForce FX series was lagging behind ATI's 9-series offerings and the Radeon X1K series had the most powerful single cards of its time, at release the X1950XTX traded blows with a 7950GX2, much like the HD 4870X2 will try to do with the GTX280 now.

I think, if I remember, it is 150w from the mobo and 75w from the PCIe 6 pin connector so it should be 225w max without an extra connector.

That could be it, I just remember there being a 150W and a 75W involved somewhere in the calculations.