Specifics on crossfiring a 4850

[bdonedge]

I have a Sapphire 512 MB 4850 (NOT THE HDMI VERSION). I have a x8 x8 mobo and am considering Crossfiring in the near future. My question is, I am unable to locate the exact same video card again from new egg or anywhere else for that matter. The only thing they have that is similar, is the HDMI version of 512 MB Radeon 4850 Sapphire. Will that be compatible? I feel like it would bring upon driver issues.

Another variation: What if I were to get a 1GB XFX 4850 card for the crossfire. Would that be compatible? Basically what are my limitations as far as crossfiring goes? I understand it's best to get the exact same card, but if that's not an option, what is my option? There seems to be a lot of 1GB 4850's for the same price that I bought this card a while ago, so if I can get one of those I will. But does it have to stay in the same brand? What are some problems that I will more than likely be running into if I don't? Thanks for the help

 

[shadow187]

If you get a 1GB version, then it will downgrade itself to 512MB of vRam, effectively losing some of its value.

But ANY 512MB version of the HD4850 will crossfire just fine. It doesn't have to be sapphire, and it doesn't have to be the non-HDMI version.

 

[wa1]

If you get a 1GB version, then it will downgrade itself to 512MB of vRam, effectively losing some of its value.

But ANY 512MB version of the HD4850 will crossfire just fine. It doesn't have to be sapphire, and it doesn't have to be the non-HDMI version.

^+1

 

[bdonedge]

Interesting, thanks for the responses! Are there any other bits of information you can tell me about crossfire compatibility before I drop this thread? For example: I know you can run certain GPU's together that aren't the same, but does it do the same thing as RAM and just downgrade itself to run at the same speed as the OG one?

 

[cromedome]

The faster card will just down clock itself to the same speed as the other one

 

[bdonedge]

One last question, will it be worth crossfiring if my motherboard down clocks the PCIe slots when they are crossfired? Basically at original speed, the one video card runs at x16 but when put into crossfire mode, it runs at x8 + x8. Is it still worth crossfiring or running a single card at x16? I know it depends on card, but I mean I guess my budget it 200 bucks if I was going to buy a new card but if crossfiring the 4850 is a better option, then spending a lot less would be ideal.

 

[shadow187]

8x/8x isn't a problem. If you can, however, sell the 4850 for $80 and get an HD5850.

Also, what's your processor?

 

[bdonedge]

I'd love to do that, but I'm not sure who I'd sell my 4850 to, to be honest. I feel like people wouldn't want to buy a used video card.

I have seen the benchmarks between 8x/8x and/vs. 16x/16x but never a single 16x vs. x8/x8. Would you have any idea if it's worth the money, or how they compare?

Also my CPU is a AMD Phenom II x3 720 2.8 ghz
I have 8GB of DDR3 1333 RAM

 

[shadow187]

If your OC your CPU to 3.2ghz (stock volts, I have the same CPU (though I unlocked the 4th core) to 3.2), you'd be fine.

The HD5850 is about equal to an HD4850x2. But the HD5850 overclocks very nicely, and will use much less power than 2x HD4850. And plenty of people buy used cards, though yours might sell for ~$60-70.

 

[bdonedge]

I have a very nicely cooled system, I may try to OC it to 3.2 then. I'm not very experienced OCing so I'll have to look up which multiplier it is exactly. That'd be a fun little thing to try.

So the 5850 is comparable to dual 4850 in x8/x8 or a x16/x16?

Also, where would I go about to sell my card if I decided to take that route?

 

[shadow187]

Download AMD OVERDRIVE, and the interface is quite simple. Here's mine;

1x 120mm Intake
2x 80mm Exhaust
1x 80mm top-exhaust
1x 80mm case-fan-intake
Mine doesn't go above 45c after about 3 hours of gaming.

The HD5850 is comparable to 2x HD4850 in either 8x/8x or 16x/16x, as both offer near-the-same performance (1% or so difference (negligible) ).

eBay is a great place to start.

 

[bdonedge]

Download AMD OVERDRIVE, and the interface is quite simple. Here's mine;
http://i43.tinypic.com/2ibkpk2.png

1x 120mm Intake
2x 80mm Exhaust
1x 80mm top-exhaust
1x 80mm case-fan-intake
Mine doesn't go above 45c after about 3 hours of gaming.

The HD5850 is comparable to 2x HD4850 in either 8x/8x or 16x/16x, as both offer near-the-same performance (1% or so difference (negligible) ).

eBay is a great place to start.

Awesome thanks for the reply. Is there a difference from OCing in the program rather than the bios? Would it be more efficient doing it in the bios? I know how, but that program looks like it would be neat to mess with.

And I wasn't aware that x8 and x16 weren't that different in bandwidth. The name of it is very deceiving. And yeah I'm a pretty big gamer and I'm trying to improve performance in Bad Company 2 and Starcraft 2 right now. And whatever future game comes out. Have you purchased a video card off of ebay before? I'd be skeptical about buying hardware off of there, seeing as there is no guarantee.

I have some very high powered fans, I don't see them overheating thankfully.
I have a sapphire card, and I'm thinking about crossfiring just because I never have before instead of going through the hassle of selling my card and buying a new model. That being said, a lot of people have said the sapphire cards aren't very reliable. Which brand would you recommend? Thanks.

 

[shadow187]

I'm using a Sapphire 4850-512MB that I got for free, and it's been working fine.

When you do it in the BIOS, it's a lot...actually I'm not sure. It's that it affects the CPU before windows even boots. What you should do is find the multiplier that's just right for your CPU (16x?), test it software-wise for a day, and if all is stable, put it into the BIOS.

8x and 16x are VERY different in bandwidth, it's just that an HD4850 does not satiate the full x8.

As for hardware off of eBay..if you're looking to sell, I'd go there. To buy....you're better off doing a google-shopping search (easy to find lower prices). A quick search gave me this below for $85;
http://www.ascendtech.us/itemdesc.asp?ic=VC512MATIHD4850

 

[bdonedge]

Yeah that's kind of what I figured the software did. Going to be testing when I get home from work.

As for x8 and x16 being very different in bandwidth, I figured that a 4850 used at least all of the x8, but apparently not. I know this is a bit off subject but what GPU's actually utilize the entire x16? And what defines something as being able to use the full x8 or x16? I don't think I've read anything that really explains why certain GPU's take up certain bandwidth.

And that seems like a good deal, I will be using a google search even though I will probably end up going back to newegg or tigerdirect haha

 

[shadow187]

Google search is great because it searches all the stores. For example, an HD5970 on newegg is $700, but I found a few for $630 using google search.

PCI-E 1.0x16 provides 4GB/s of transferring power. 2.0x16 provides 8GB/s (PCI-E 1.0x32). Really the only way to saturate this speed is by extreme SSDs in a RAID 0 configuration. I'm not sure how to figure out how much bandwidth a GPU uses.