Two 7800 GTXs in SLI or a single $200 graphics card?

[Red Storm]

Originally posted by: themisfit610
LOL you guys fail - take the bickering elsewhere. This is a thread about SLI 7800GTX or a new $200 GPU. Clearly a $200 GPU is the way to go. End of discussion...

~MiSfit

And that $200 GPU should be the 4850 IMHO.

 

[Denithor]

Originally posted by: Rhythmdvl2
Wow... just wow. I had no idea there was such a rivalry-like schism between the two!

So let me get this straight: Linking two cards (in either case) isn?t the equivalent of roughly doubling initial capacity. That is, two 256MB cards won?t be the same as a single 512MB card minus a bit of overhead, and two GPUs won?t necessarily double their ability (again, minus a bit of overhead). Not that there wouldn?t be some improvement (two 7800s would substantially(?) outperform one), but a second 7800 won?t come close to an 8800. It might be the way to go if I only had fifty bucks to spend, but prices are so low that I should be able to easily leapfrog well over that setup without breaking the bank.

I?m assuming the above is true for similar reasons to why a second core isn?t really like doubling your computer. While some processes run better, most need to have been written for multiple cores or else they can?t take advantage of the extra processing power (I?m on a 32 bit XP system-I don?t know if a 64 bit OS changes things). Does that analogy even weakly hold up? Am I right in my understanding of SLI/Crossfire improvements?

How does it work within the same basic class? That is, forget about comparing two 7800s to one 8800?what if someone (unfortunately, not me) had around four hundred dollars to spend? Given what?s available now, would linking two $200 cards achieve markedly better performance than one $400 card? If not, who the hell is buying SLI/Crossfire? Does it only make sense if you can put in two of the upper tier cards?

My head hurts. Damn marketing departments!

If you?ll bear with me, I hope to make sure I?m not overlooking something major?the rest of the hardware, since that?s not changing at the moment. I don?t believe my mobo (Asus M2N4) has a PCI-e 2.0 slot, but I gather they?re backwards compatible. But that aside, is there any chance that given the rest of the rig (AMD 64x2 4800/2GB RAM), I could end up spending dough on capacity that so far outpaces my system that I?m wasting money?

Thanks!

You've actually hit pretty close to right on there. SLI two cards, if drivers and game are optimized, you get 2xPerformance. Not the case usually... Typically you get anywhere from 1.0 to 1.6xPerformance (some games don't even "see" the second card so no effect at all). This holds true for both SLI and CF options, it all depends on drivers and game optimization.

Typically the only time people around here will recommend SLI/CF is if you are going to do it as part of your initial build, like today it makes no sense to drop in a second 7800GTX when instead you could just go with a single 8800GT for $130 or a 4850 for $200.

Now, if you want top end performance today, without spending $500-650 you could instead pick up a pair of 8800GT for SLI for around $275 and in many games match or beat the performance of a GTX 280. For around $350 you could CF 2x4850 and get even higher (except that your board will not support CF). You also have to consider that your CPU may hold you back a bit, so SLI 8800GT or could be your best option.