UP grading PC, Advice please!!

[HotStuff]

First of all thank you to everyone who gave me advice last time on whether to go with Dual core or single core. I have decided to go for single core, main reason being that BF2142 is using an enhanced BF2 engine and will have no significant (if any) performance advantage on dual core.

So am going for:

Intel 3.8GHz, 2Mb Cache with HT

As for graphics cards, this is where I need the advice, is it worthwhile me going SLI, and getting two of:

nvidia 7900GTX 512Mb (http://www.ebuyer.com/UK/product/107806)

or should I just stick to one. Will I get a significant performance advantage with 2 cards over one with this processor?

Anyone ?????

 

[Pestcontrol]

I'd say get one card now, and get another when you actually need it. As BF2142 seems to be scheduled for a Q4 2006 release, prices for a second card will have dropped significantly by then, you could even get one second hand. Also there's still an advantage for dual core, especially with SLI, because the graphics card drivers, which take a very significant chunk of CPU time, can utilise the second core (this overhead is such a problem reducing it is a major goal of DX10 development). I don't have any numbers for you right now though.

Best would be to get a cheap cpu or wait a month so you can get a Conroe based dual core. They will pwn AMD all over the place for at least a year, for both single and multithreaded applications, it's really worth waiting for.

 

[Tetsuo_Shima]

In the same vein, without bumping my own thread, is the dual core AMD Athlon 64 X2 5000+ AM2 skt any good? Im a bit curious about the 2x 215kb cache compared to the 4400, 4800, FX's 2x 1mb cache. According to THG, it doesnt seem to impact performance, but Id rather be a bit wary.

And out of curiosity HotStuff, what system are you currently running? If you're upgrading to a single core, will it still be suitable for the long-term?

 

[LynxGB]

as for what pest said about buy one now and one later - its not such a good idea! Although cutting cost it would be great - but you then loose the 100% gurantee that your card will be avaliable to buy in upto a years time. Which would then mean if u want sli you will have to buy two new cards!!!! And second hand graphics cards - are you mad, last owner 15 years old overclocked it to point of meltdown - t minus 2 days until it stops working with no warrenty - excellent!

 

[Macca]

I don't think pest was talking about buying one a year on. If you wait atleast a couple of months, then 7900 chipset will fall rapidly in price. I wouldn't recommend buying a second hand card (not that I have any experiance ) unless it's from a trusted source.

It's also maybe better waiting for the AM2 before you go buying the all hated pentium.

Anyway you can take my info with a pich of salt as I am not the sharpest knife in "Pests pants" when it comes to this sort of thing .

 

[HotStuff]

Tetsuo, I am currently running on a

3.2GHz, 1Mb Cache, HT
on a
nvidia AGP 6800GT 256Mb

I religously upgrade my PC every 2 years and this July is defintely my upgrade date. I usually have no problem upgrading but the choice with an array of new processors coming out this year and the spanner of deciding if going is SLI is a good idea, it is creating havoc in my decision making process.

I think as LynxGB said if you are choosing to go SLI, you really need to buy both cards at once to ensure compatibility. I understand that people have already offered me other options. I accept what Pest control says about DX10 and Dual core processors supporting SLI to reduce workload on main processor.

However can anyone answer the original question I asked which is, "Will I get a significant performance advantage with 2 cards over one with this processor?"

 

[Tetsuo_Shima]

Yes, yes you do. The increase in performance is far more noticeable on games that require higher shader technology, so BF2142 will benefit immensely if that is what you are hoping to utilise it for. Battlefield 2 and CS Source will still receive a decent performance boost, but not so much so as games that can really put the pedal to the metal.

As a sidenote, I do belive that AMD processors cope far better with SLi technology; but I dont see any problems on running it with Intel...

I just noticed something there that I missed, your 6800GT is an AGP. Does your PC not have PCI-Express capability? If you buy two AGP 512 7900s then you're going to pay a hell of a lot over the odds and experience a bit of power loss, if I'm not mistaken.

 

[Pestcontrol]

Tetsuo: I recall 1MB of L2 can improve the minimum framerate, whilst not doing so much for average fps. But as it stands now it seems it's indeed not that important. The impact of cache highly depends on the software you're running, it will differ between different kinds of work and it may differ between two games. An X2 5000 will be a good chip, assuming it is affordable to you.

Macca: yes, that's what i meant, although second hand isn't necissarily bad if you feel you can trust the buyer. Finding someone local so that you can get your hands on the hardware and assess the seller before buying is always best. Anyway, it's best (but not absolutely required) to get two identical cards, that doesn't mean you need to buy them at once, if you really don't want to take a risk you can even get them from the same retailer. The fact that one card has been used more than the other makes absolutely no difference at all, remember they are electrical devices, not mechanical. Personally i don't feel it's worth it as an initial investment, only as an upgrade.

Also would you please get out of my pants, thank you.

Hotstuff wants to buy Intel so i'm not going to challenge that, and quite frankly with the upcoming Conroe (Core2) processor, which has it's release date moved forward from Q3 to july, it will be probably time for me to start recommending Intel instead of AMD to people, even if AMD as a company has my sympathy, i'm professional enough not to let my recommendations be influenced by that . Prices have already been announced, all that's left is the reviews to see exactly how it performs, how overclockable it is, if the existing motherboards are all compatible and if it surpasses AMD's offerings in price/performance as well as raw performance.

 

[Pestcontrol]

I just noticed something there that I missed, your 6800GT is an AGP. Does your PC not have PCI-Express capability? If you buy two AGP 512 7900s then you're going to pay a hell of a lot over the odds and experience a bit of power loss, if I'm not mistaken.

I would assume he upgrades his motherboard as well unless i misread something. AGP cards are not suitable for SLI, and you won't find a consumer motherboard with two AGP slots.

Hotstuff, the only thing that can answer your question is a benchmark, but if you don't buy two cards at once you can also do some testing yourself to see to what degree your games are GPU or CPU limited. In the case of a CPU bottleneck, adding another GPU will not help, the increased overhead may even reduce fps, it will however enable you to play at higher resolutions and detail settings, and heavier antialiasing, features that only tax the graphics hardware. Strictly speaking the highest possible framerate on a system will be decided by CPU performance whereas the highest possible resolution and detail are GPU dependant.

Also be aware that dual core is the future and with the crossover of sold dual core vs. single core processors happening soon, future drivers and operating systems will make increasingly better use of it, even with games that do not themselves benefit.

 

[decky101]

I think one card is enough but you can always come back later and upgrade.

 

[HotStuff]

I have been driving myself mad trying to decide on choice of processor, I am begining to think that a

Dual core 3.6Ghz Intel

is now a better choice than a single 3.8Ghz core, not because of the DX10 supporting dual core better (BF2142 will still be DX9) but becuase you can associate one core with one application, ie BF2 or BF2142 or any game. This leaves the other core to do all the other stuff that has to be done. The important thing here is that the loss of 200Mhz of speed I think will be more than compensated by the fact that one 3.6GHz core will be taking care of the game and nothing else.

Aggree/disagee?

As for dual SLI, from my fact finding,It appears that the average framerate improvement is only about 36% over that of a single card running at 1280x1024.

The main performance advantage of dual SLI occurs if you play games at ridiculous resolutions like 1600x1200 and up with AA and AF up at full, a dual SLI can cope with it. But who plays their games at that high resoultion? Personally I play my games at 1280x1024 which is 56 lines short of HD standard.

See http://www.nvnews.net/previews/nforce4_sli_intel_edition/page_5.shtml as an example.

I was thinking of getting 2x256Mb graphics cards in SLI. Would that be better than getting a single 512Mb card? I couldn't find any benchmarks to compare - any ideas anyone?

 

[Pestcontrol]

The only time you need to assign a task to a specific core is when it is broken otherwise, or when you're benchmarking. A single task may still be multithreaded, and even if it isn't, windows is clever enough to schedule all the rest to the other core, it doesn't improve performance positively to force a task to this or that core, although no doubt there are exceptions. It may even break any multithreading employed by the graphics driver.

2x256MB cards is faster than 1x 512MB provided all else is equal and you don't have a game actually using that much memory. After all, you have twice the graphics processing power, and memory only hurts performance when a game needs more than you have.

However, if you chose to go SLI, the high detail settings that you will use (or there'd be no point in SLI) will eat more memory. I'd say get a single 256mb card and play at your regular res and settings or two 512's and max it all. Two 256mb cards may end you up in a situation where you have the power to run high settings at high framerates, but not enough memory.

I don't know of any article actually testing this though, so consider it speculation for the time being.

 

[thatbloke]

Or get two of the cards mentioned in this slashdot article. That'll sort you out

/me drools

 

[elDiablo]

Well, thatbloke, seeing as the dual SLi 7800's have been out for a while (and as you should know I've been drooling over them for a while), you can probably guess that I'm getting a bit dehydrated now!

And Hotsuff, being a keen watcher of SLi (nVidia fanboy at heart! ), I can say that the whole point of SLi was to make playing games at higher resolutions possible. As a single 7series card can quite easily power most games at 1280x1024, adding another at that resolution will not do much for you. It will add more on board memory in effect (hence the small boost in FPS).

Originally, when the SLi was first introduced, the idea was that playing at larger resolutions was possible as the two GPUs could work together to do all the magic stuff to make your games look pretty. This lead to the big screens that we have been seeing (the 30" one from Dell, for example). However, not many people have big screens (I have 2x 17"s that have a max res of 1280x1024). Now, the clever people at nVidia thought, "Hmmm... what else can we use this power for?". And so was born the SLi-FAA of goodness. This pretty much means that you can set application profiles for your graphics card, with certain AA settings being implemented when a certain exe is run. If BF2.exe is running, your primary card will do the same job as it was before, but your second one will be SOLELY for AA and the such likes.

This is a GREAT gain, as you can put EVERYTHING up to max, one card will do the main work, and the other one will make everything look BEAUTIFUL.

Now, the second main gain of a dual SLi set up is dual screens. I mentioned I have 2x 17" screens. This is due to me being a geek and all, but is handy (having TS and xfire on one screen, while I play games on the other). However, having only 1 graphics card means that I can't run my graphic-intensive (Doom3) games at 1280x1024 (as I effectively have a screen resolution of 2560x1024, even though games only span the primary screen). So, adding a second card will help a LOT with dual screen set up (as long as you don't want the SLi-FAA as much).

Hope this makes a bit of sense, if not, I can write a whole other spiel with links and the such if you want

 

[Pestcontrol]

Having two 256Mb cards does not mean that you have 512. Each card will need to have all material required for the entire scene in it's local memory. Accessing any external memory, be it the other card's or the system memory, is far too slow. It's just like with the Voodoo 2 and 5, and the original SLI.

Also, the SLI mode you mention, the third after AFR and SFR, that gives the extra AA, to my best knowledge DOES NOT dedicate one GPU for AA calculations. What it does is have each cpu render a scene with for example 2xFSAA with different subsamples, and then combines the images now having a total of four subsamples per pixel: 4xFSAA. It's clever, but the impact of FSAA is not so great as it used to be, 4xFSAA does not halve framerate compared to 2x, and the cards are doing a lot of double work as each renders the entire scene every frame.

Couldn't find any benchmarks of it yet.

 

[elDiablo]

Sorry, should have explained myself more. I wasn't trying to say you can quickly access another card's memory. However, as SLi works in one of two modes, it is possible to use the different boards in single frame rendering mode. This means that each board does the maths for a portion of the screen, with the frame buffers being joined just before sending to screen. This means that you can (theoretically) use 512Mb of onboard memory (if both cards have 256Mb onboard).

It is also possible (with the Dual cards that thatbloke mentioned) for 2 GPUs to use 512Mb (on a single board). Put that in SLi you get a lovely 1Gb of memory (in single frame rendering mode)

As for the FAA, guess I was wrong. I read a few articles on it, but it seems you were right and I was lied to

 

[Pestcontrol]

You might as well assume i'm right on the memory thing too then. Also there are three SLI modes now, AFR or alternate frame rendering, and SFR, split frame rendering (what you call single frame), were the original two, the new one is just called SLI i believe and doubles your antialising. Thinking about it some more i suppose one advantage of this mode is that it has less driver overhead compared to the other two.

Still, in this case 256+256=256 and not 512. The driver does not know where on the screen a texture, static mesh or other peice of material is, so it has to upload everything to both cards, framebuffers and offscreen surfaces are also duplicate (and rendered in full res even in SFR mode), nothing is shared between the two cards. If a game has 150MB of textures that means there are 150MB of textures in card A and 150MB in card B.

What IS true however is that it will take up 1GB of memory space (windows maps graphics memory twice), and so for 512MB cards in SLI, 2GB, and with quad SLI 4GB. This also means you'll need a 64 bit Windows XP for the heavier SLI setups.

 

[HotStuff]

Right thanks guys for the info, though I think it has raised more questions than answered.

I have no intention of playing games at resolutions above that of 1280x1024. Yes I understand that SLI is for increasing detail without loss in frame rate/playing at very high resolutions.

Is the purpose of having more memory on a graphics card not to support higher resolutions? So would 2x512Mb be necessary for playing games at 1280x1024? I like to have detail, textures up high but I don't really care about AA/AF.

I am just trying to buy efficiently here, according to the link I provided earlier, dual SLI appears to provide about a 36% framerate improvement in 1280x1024 resolutions, but up to 80% framerate improvement with AA/AF maxed out or 2048x1536 resolution.

The crux of my question is what is important to give good framerate, not AA, AF, FSAA etc at 1280x1024? Is it the memory or is it 2XGPU? This was the logic behind my original question of whether to get one 512MB or 2X256MB. The difference in cost of 2x256Mb and 1x512Mb is practically non existent. If I am going to get an average of 36% improvement in framerate then for me that is worthwhile getting 2x256Mb.

However the argument you guys have made is that the only real advantage in having 2x256Mb is that you get 2xGPU as the memory is still effectively 256Mb. So as I don't care about AA/AF/FSAA etc, would I be better getting a 1x512Mb with one GPU core?

I realise that the answers you guys give may only be speculation as I can't find any benchmarks.

 

[HotStuff]

Just found this quote from

http://www.hardocp.com/article.html?art=NzkzLDE0LCxoZW50aHVzaWFzdA==

It's an older review about 2x128Mb Daul SLi

"As expected, SLI helped with performance in most games. Remember, with SLI you are not doubling the framebuffer size. Two MSI GeForce 6800s in SLI still only have 128MB of local video card memory available to them. This fact creates something of an imbalance in our opinion. Here you have two GeForce 6800 cores in SLI, which can greatly increase geometry performance, but you are limited by a 128MB framebuffer. It is like driving a new C6 Corvette with a speed governor set to 85MPH. The SLI setup has great geometry performance, but you do not have enough memory for high resolutions with AA. To put it quite simply, SLI is all about high resolutions with high levels of AA."

Does this help?

 

[Pestcontrol]

That HardOCP story was exactly what i was trying to explain.

As your card will be faster than the 6800GT tested, and you have even more geometry power since you don't use AF, you will very likely be CPU limited. There would be little point in SLI for you if you don't play on higher resolutions and enable the goodies.