RAM: Quality vs Quantity

[Spider]

Since there are people here more knowledgable than me, I figured I'd try and get to some of the gory details of computer building.

 

I have a friend who is in the process of building a gaming computer and will start an upgrading process myself within a couple of months. He asked me today whether it was better to buy 2 GB of faster memory or 4 GB of no-name memory. And I really had no idea. I figured more is better, but up to what point? (and yes, his system will be Vista ready, so he can make use of 4 GB)

 

Bonus question: When shopping for a motherboard, what current one gives you the best bang for your buck? It needs to be SLI-ready, so that kinda narrows it down a bit I suppose.

 

Bonus question 2: How common is it that graphic cards require a direct connection to the PSU. I have (and my friend is considering) an Antec Phantom, a fantastic PSU with only one graphics card cable. So if it's becoming the norm for the graphics card to require it's own power, the Phantom isn't exactly SLI friendly. My card doesn't use it's own power, but it's two years old, so I suppose a lot can have changed in those regards.

 

That's all for now I think.

[mkreku]

The clock speed and timings of the memory are important for performance. But brand names are usually only important for those who consider overclocking their memory modules. No-name memory is perfectly fine for everyone who doesn't overclock their gear, as long as you don't buy the absolutely cheapest sticks (with 4300 and 6-6-6-18 timings or something..).

 

Motherboards is a jungle so I'll leave that to someone else who's not as lazy as I am (but know that AMD is releasing their new AM2+ socket soon soyou might want to wait for that).

 

When buying a PSU, I'd really recommend at least 500W and modular cables. Modular cables means you can connect only the cables you need and you can buy exactly the cables you want to change later. I have a Cooltek 600W with modular cables myself. Highly recommended.

 

I use the Antec Phantom at work. It's quite nice.

[metadigital]

Matias' comments on RAM are pretty spot on; some of the cheaper box-shifters supply RAM that is measurably slower than the premium stuff, even when set to the same timings (wiki).

 

There is a new, lower-price SLI-ready nForce chipset motherboard for about

[Wistrik]

My relatively limited experience is that 2Gb of fast memory is better than 4Gb of slow/mediocre memory. (System memory is already slow enough, which is why processors have L1/L2/L3 caches consisting of superfast memory.) Business and non-entertainment applications don't care as much about performance because they spend most of their time waiting on the user for input, but games must render scenes and run fast refresh loops constantly, regardless of what the user is doing. Games tax a computer more than just about anything else, except perhaps benchmarking software and commercial renderers (and other specialized applications), but in a game I tend to care more because the frame rate directly corrolates to how smoothly my commands and actions are performed.

 

I can't answer the motherboard question(s) because the scenery is going to change by the time I'm ready for a big upgrade. The new Penryn and Barcelona cores will be out by then, and I'm waiting to see which one ends up being the better buy. That'll determine which motherboard I get. SLI is a given, and probably SATA2. I don't need video processing because I don't watch DVDs on the computer.

 

We'll probably see GPU power cables from here on out, so don't get a PSU that doesn't support them. Thanks for the tip on the modular PSU. I hadn't considered that before.

[Diamond]

I guess that depends on how much you need to avoid using the swap. I have 2Gb, and swap space is never used whatever memory hog I use in my system. So for me the bottleneck is memory speed now. I can't imagine you needing more than 2Gb of memory on a desktop computer. On the other hand, I haven't played any games lately, so someone correct me if I'm wrong.

[SamuraiGaijin]

RAM: generally speed (DDR2 533 vs 667 vs 800 vs 1067, etc.) is more important than latency (CL4 / CL5 / CL6).

- In general, I have always bought the fastest memory that my motherboard officially supports, but I usually buy performance for gaming.

- If you're planning on doing any media editing, you probably want to go with 2x 2GB sticks now (so that you have room to upgrade later).

- If all you're going to use the computer for is typical web surfing, document crunching, and gaming - 2x 1GB is more than enough (for now).

 

MOBO: It depends on your budget, but right now I'm helping a friend build a low budget (i.e.: about $1000) gaming box, and the nForce 650i SLI looks really good right now. I'm very happy with my 680i, but the differences between the two probably don't justify the premium price.

 

VGA: Any decent modern card requires external (i.e.: not from the slot) power. That said, while there are performance gains to be had with SLI, you're generally better off going with one more expensive card than two cheaper cards - unless you plan on multi-monitor (i.e.: more than two) ops. (My friend, for example, wants to set up a three-monitor rig for MS Flight Sim X.)

 

PSU: I recommend more than 500W and concur with the modular cable suggestion ... I'm very happy with my SilverStone SST-S60F (600W Modular). If there is any component in you box where you cannot afford to cut corners, it's the PSU.

[Spider]

Thanks for all the replies. They helped a bit. In regards to the PSU, a lot even. The SLI option is more a future-plan than anything immediate. Ie get a good card now and in a year get the same card when it's cheaper rather than doing a full upgrade at once. Or at least having the option of doing so.

 

But then I talked to my friend again who had talked to some other people about RAM and then it got confusing. I tried looking at the wiki link Meta provided, but it's a bit too technical for me to get into (as in the language, not the concepts as such). From what I could piece together from a phone conversation just now, my friend had learned that buying better memories (as in speed) was worse than buying worse memories, because the better ones couldn't be used in dual channel mode or something like that.

 

Specifically, it was better to buy PC6400 memories rather than PC8000 (the same amount) because the processor (E6600) couldn't communicate fast enough with the memories for the higher speed to come into play at all. I didn't quite get it and thought it sounded a bit weird, so does anyone know what he meant? Basically, all other things being equal and money not being an issue, what type of memory will net the best performance, with a Asus n680i and Intel E6600 (the stuff he'll most likely be getting). An explanation as to why would also be appreciated.

 

Here's your chance to show off your knowledge.

[Wistrik]

I'd look up the motherboard specs if you can find them. (Asus' site would be my first visit.) The motherboard determines which memory configurations will be DDR/2 and which won't. There are usually four slots for memory, and the type of memory and which slots you stick it into determine the final result.

[taks]

My relatively limited experience is that 2Gb of fast memory is better than 4Gb of slow/mediocre memory.

this _used_ to be true, though not necessarily anymore. anandtech did a test with all the new processors and found that even budget RAM performed nearly as well as the high-end stuff in stock systems (i.e. no overclocking). the memory bus is so fast now, more is better than faster _unless_ you intend to overclock. in general, the bottleneck is going to be reads/writes to disk, so the more RAM you have, the less disk accesses you have. regard this as a very loose rule of thumb since the landscape of computer architecture has changed dramatically in the last few years.

 

taks

[taks]

Specifically, it was better to buy PC6400 memories rather than PC8000 (the same amount) because the processor (E6600) couldn't communicate fast enough with the memories for the higher speed to come into play at all.

what he was getting at is that after all the latencies are calculated in, the effect of slower memory is almost negligible in the long run. memory accesses are very bursty, and most applications are dominated by RAS/CAS latency (i.e. the hit you take every time you start an access) because it is rare for _all_ of the data you need to be located within a contiguous space in memory. the speedup from transferring data at a higher rate works out to almost nothing.

 

as far as i know, any current processor can easily stream data at the rate it will come out of even the fastest memory, but that situation never arises in practice.

 

taks

[Bokishi]

High quality ram is not really a necessity, especially in games where differences will be 2-3 fps higher. Being SLi ready doesn't mean anything either, unless you like your overclock being managed for you, in which I don't, so I leave the option disabled.

[SamuraiGaijin]

... my friend had learned that buying better memories (as in speed) was worse than buying worse memories, because the better ones couldn't be used in dual channel mode or something like that.

 

Specifically, it was better to buy PC6400 memories rather than PC8000 (the same amount) because the processor (E6600) couldn't communicate fast enough with the memories for the higher speed to come into play at all. I didn't quite get it and thought it sounded a bit weird, so does anyone know what he meant? Basically, all other things being equal and money not being an issue, what type of memory will net the best performance, with a Asus n680i and Intel E6600 (the stuff he'll most likely be getting). An explanation as to why would also be appreciated.

...

The above concerns are not valid ... the front side bus speed (how fast the CPU talks to the Mobo) and memory speed are asynchronous (not linked) on the 680i or any other current-generation motherboard.

 

That said ...

(1) most 680i motherboards only claim to work up to DDR2 800 (PC6400) ... but higher speed RAM might work

(2) the Core2Duo FSB runs at the same frequency as PC8500 (1066 MHz)

... so I'd bet whoever you friend was talking to is mixing up his apples and oranges.

 

For the best chance of success ... I recommend using whatever memory best fits your friend's price range that has been tested to work with the mobo he's picked ... for example, on the ASUS site, the "QVL Download" button on the left of the screen gives you a list of certified memory and what modes they work in.

 

My 2x 1GB sticks of Corsair XMS DDR2 800 (PC 6400, CL5) work great in dual channel mode (so far) with my E6600 and BFG 680i. I haven't tried overclocking yet (no real need to) and can't justify the price premium for faster RAM (especially when there's no guarantee that it will operate at the rated clock speed), so I don't know how faster RAM compares.

Edited May 8, 2007 by SamuraiGaijin

[Spider]

Thanks a bunch, I'll be sure to pass it along (and keep it in mind for myself when the time comes).