4870 Crossfire + a 4850?

I just bought the following:

Asus P6T X58 MoBo; Intel i7 950 CPU; Corsair HXW 1000W PSU; Corsair 6 GB DDR3 RAM; 2 HIS 4870 1GB video cards; XCLIO ATX Full Tower Case; Western Digital VelociRaptor 10,000 rpm 300GB HD SATA II; LG DVD Burner; Windows Vista Premium 64 bit. With shipping, I spent a little over $1,900.00 for this rig.

I currently own an upgraded Gateway FX 6800-10ewith an i7 920 (stock), 700 W PSU, Sapphire/XFX 1 GB 4850s in crossfire. I'm going to pull the XFX 4850 out of the Gateway and give the PC to a relative.

My question: In my new rig (above) with the 4870s in crossfire, I was thinking about taking the XFX 4850 and add it to the 4870 crossfire setup to have a 4870 x2 + 4850 Trifire setup. I've read that video cards will always revert to the lowest capable card, thus making my 4870s + the 4850 in trifire equal to three 4850s in trifire. Is this true? Will the two 4870s and one 4850 act as though it's three 4850s in trifire or will I have the performance of the 4870s in crossfire plus a little boost from the XFX 4850 card?

Thanks in advance.

they will all behave as they are all 4850s

I'm not sure why my reasons for doing this is relevant in this discussion; but if you need to know, I'm giving my gateway to a very close relative who does not know anything about gaming, let alone graphics cards and what not. As such, having an i7 920 with a Sapphire 4850 1GB video card is far beyond what this person requires for her limited computer skills and needs. That's why I'm pulling the XFX 4850 out of the rig and if you read my post, I already purchased two HIS 1GB 4870 cards. Why let the XFX4850 go to waste when I have an empty PCI 2.0 x16 slot onmy newAsus MoBo.

Anyway, thanks for the response and from reading the above posts, it seems as though my original assertion regarding the 4870 + 4870 + 4850 = 4850 x3.

no they wont behave like 4850s

a 4870 will behave as a 4870 and 4850 as a 4850

i have done this setup on my pc and they both work at their own clocks

just see that all of them have equal vram

or u will waste ram

no they wont behave like 4850s

a 4870 will behave as a 4870 and 4850 as a 4850

i have done this setup on my pc and they both work at their own clocks

just see that all of them have equal vram

or u will waste ram

mafia97

No it won't. The workload is split equally amongst the 3 gpus and the even if the performance will be greather than 2 4870, it won't be the same as 3 4870 because as i said because the 4850 cannot keep up with the other 2 4870. So the 4870 will slow down to the speed of the 4850 because they have to wait for the 4850 to render his third of the screen or his frame in the case of afr....but it's better anyway than having "just" 2 gpus

Sounds like nothing but a waste of electricity.

I don't know why you would do this. I understand for nVidia as a person can do dual 260's/285's with a 9800 GT for dedicated physics which actually helps, but I wouldn't think that your gains would be large enough to actually make the 4850 worth it.

Performance will be the same as 4850 CF. Just google it. I read it @ Hardware Canuck.