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AMD Phenom, Vista 64-bit, 2GB or 4GB?

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October 27, 2007 6:33:45 PM

This being my first post, I want to get right down to it :) 

I am planning to get a new rig in the 1500-1700 euro range sometime around Christmas. I'm fairly certain I want to get a Phenom X4 CPU, rather than an Intel Penryn (there is no way I'm waiting for the Q1 mainstream launches, then I might as well wait for Nehalem :lol: ).

So I'm looking at something along the lines of:

Phenom X4 @ 2.4GHz+ (that would be the 9600+ if VR-Zone is to be trusted)
ASUS M3A32-MVP Deluxe WiFi or similar (790FX)
RV670 512MB @ 825MHz (HD3800 ?) or an NV 8800GT
2x 320GB Seagate Barracuda 7200.10 (RAID0)
Vista Home Prem 64-Bit

I kind of want DX10, though it seems to be pretty useless at the moment, so I'm still considering XP64 as a less driver-troublesome alternative.

This might all be rather speculative (seeing most of the parts aren't even on the market yet :( ) but I'm really wondering about the RAM...

I have about 200e to spend on RAM and I do want 'moderate' overclocks.

So what I'm really wondering at the moment is whether I'd be better off getting 2GB very high quality RAM (1066MHz good OC), or 4GB of something cheaper like 4x 1GB G.Skill DDR2-800 F2-6400CL4D 4-4-3-5.

I've heard that C2Ds pretty much have their hands full with 2x 1GB DDR2 1066MHz running in Dual Channel, and that there aren't really any performance improvements after that, for AMD processors however I haven't been able to find any comparisons... But I would imagine that the integrated memory controller could make better use of higher speed and larger amounts of RAM.

Vista does seem to be a bit extreme when it comes to the size of it's page file, so the extra RAM might be good, but then again it might be using up valuable $$$ without paying up in terms of gaming performance ;) 

Is it possible to run 2x 1GB + 2x 512MB in Dual Channel mode?

What do you guys think? Any particular models come to mind?

Thanks for Your Help!

-Arminius

P.S. - A little bit beside the main issue, what do you guys think about Vista-64 vs. XP64?
October 27, 2007 7:19:43 PM

I'm not sure what driver issues with Vista x64 you're talking about. Pretty much everything has drivers now, minus a few sound cards.

In the battle of Vista vs. XP, Vista wins in my book.

Vista doesn't need a page file. I have 2GB of RAM, and I only enable a page file when I'm about to play Supreme Commander.

I would go with 4GB. It would make sure that you don't need a page file at all. I actually have the G.Skill ultra low latency RAM you mentioned, and I have it running at 980MHz at 5-4-3-5. Your results will vary, but it should be in the same ball park.

As long as you have a good video card (I'd recommend an 8800GTS) you won't notice the performance hit.

Yes, it is possible to have that RAM combination, but I'd recommend keeping each stick the same model # for best performance.
October 27, 2007 7:35:47 PM

I'm waiting for the Phenom processor myself, though i will look at the benches when it comes out before making a final decision between it or an Intel CPU.

That said, when going to Vista 64 or XP 64 Pro, 4 gig of ram will work better than 2 gig of ram. Get a 2x2 set rather than a 4x1 set, as the 2x2 will allow 1T timing while the 4x1 will restrict you to 2T timing. If the cost is a problem at the moment, I'd get one 2 gig stick now and one 2 gig stick latter. That will give up dual channel for the moment, though the advantages of dual channel are a bit questionable, but this is a planning on the future minded idea. As far as running two sticks of ram in 2x1 gb and two sticks in 2x512 mb, it will give you dual channel, but restrict you to a 2T timing which will slow everything down.

In comparing XP 64 Pro and Vista 64, I've used both and have a preference for XP 64 Pro. XP 64 is more stable, uses less resources and is much faster. In my opinion, the one and only advantage if Vista 64 is the ability to use DX10. If there was a way to make DX10 work on XP 64, I'd drop Vista in a second. To put it another way, you probably have read how games slow down a lot in Vista compared to XP, whether its XP 32 or XP 64. I like my games to keep good frame rates, so I prefer XP 64 over Vista 64.

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October 28, 2007 11:24:59 AM

One of my friends had a number of driver problems in Vista-64, mostly sound related ones like headsets not working, 5.1 surround sound not working, and a few problems with input devices as well.

You said "Vista doesn't need a page file." How do you disable it then? And what happens if the system memory does get completely filled up? (Of course 4GB should keep that from ever occurring)

More importantly though, you recommended going with 2x 2GB rather than 4x 1GB because the latter could only be run with 2T timings.

I've heard that in games 1T/2T only makes a 1-2% performance difference, wouldn't that be remedied with the higher overclocks that 4x 1GB could provide? Or do 2x 2GB kits overclock just as well?

I'm certainly having a hard time finding 2GB sticks that will run at 1000MHz (most of them meant for 800MHz), and I haven't seen anything that will run higher than that...

And how much of performance improvement am I likely to see with 4GB RAM instead of 2GB, with an AMD processor? (Like I said, I've heard the C2Ds don't really get any performance gains after 2GB)

-Arminius

On a side note, there is an open source project that is trying to port DX10 over to XP. Have a look at:

http://www.fallingleafsystems.com/compatibility/

I haven't tried "Alky for Games" myself (no DX10 games), but you could give it a shot and let us know if it works :p  Then there'd be no need to buy Vista for DX10!
October 28, 2007 11:42:46 AM

Ok i got 4gigs of DDR2-800 un der Ultiamte x64 and my system boots as fast my XP x64, and there is no performance decrease.

HOWEVER, depending on your mobo and ram combo, you may have problems installing vista 64 with 4gig of ram isntalled (BSOD during installation)

if that is the case then remove 2 gigs, install vista, install a microsoft patch realting to this issue, put back the 2gigs.

And if you have a Creative X-FI then your gonna have A LOT of problems (a bee hide in your speakers)

Over all, i prefer Vista to XP by a landslide even though it has some drawbacks.

But defenitely 4gb cause my Vista at idle (Desktop stuff only) uses around 1.2g of my ram.
October 28, 2007 11:52:57 AM

I just found: G.Skill 4GB Dual Kit DDR2-1000 F2-8000CL5D-4GBPQ 5-5-5-15

For only 190 Euros... Anybody know anything about this RAM? It looks pretty good to me...

But back on the 4x 1GB front, for only 75 euros, I found:

Transcend 2GB Dual-kit DDR2-800 PC-6400 4-4-4-12 (aXeRam)

A similar model, has heat spreaders though, uses the same memory chips (Micron D9GMH) and PVC, but runs at 1200MHz (using higher voltages). Does that mean that with adequate cooling I could get the 75e 2GB Dual kit to run at 1200MHz as well?

Cause 4x 1GB @ 1200MHz sounds a lot better than 2x 2GB @ 1000MHz to me... even if I have to resort to 2T timings then... Not to mention it would be 40 euros saved :D 
October 28, 2007 2:04:20 PM

I'm not sure why you want DDR2-1000 ram. So far I've never seen an AMD motherboard that supported anything greater than DDR2-800. The final timings may increase when overclocking up to around DDR2-840 or so, but that's about it. That's where the Micron D9 ICs have proven so good, for overclocking to DDR2-840 speeds.

Having four gig of ram is something more needed by 64 bit OSs. XP will only use around three gig total, which means an unbalanced ram set. That's why so many people use a 2x1 configuration. A 2x2 confirguaration with a 64 bit OS, besides giving a 1T timing, leaves room for going up to 8 gig with a 4x2 configuration if its ever needed. But, if a 4x1 set is a lot cheaper and fits your budget better, then that will work as well. I'm not familiar with Transcend (aXeram) myself, so can't advise you on it.
October 30, 2007 4:33:53 PM

Well there's the thing, the new AMD chipset, 790FX WILL support speeds of 1066MHz, and you said the 'final timings', sure the timings might go up quite a bit if I got higher than 840MHz, and the overall access times may get higher, but certainly the increased read speed should make up for it, or...?

Is anything over 800-840 MHz just pointless? Are those speeds just beyond what the system can handle? Or are any possible performance gains canceled out by the much increased timings?

I'm rather new to OCing memory, so I really don't know at what point these things "break even".
October 30, 2007 5:52:49 PM

I haven't seen much on the details of the 790FX chipset, so can only make guesses. I've read a couple reports that predicted 1066 speed, but also a couple that said it will stay with the traditional 800 speed. Perhaps there will be two versions of the board, but I don't know. I think we will just have to wait and see it when it comes out.

Its not that anything over a speed of 800-840 mhz is pointless, but rather that the way AMD programs the chips and mobos, the ram speed clocks down if pressed higher. This is typically seen when someone raises the FSB (hypertransport if you will) to something above 220, thereby having the ram clock down to 333, which is doubled to a 666 mhz speed. The introduction of the AM2 lines of CPUs confused the matter even more because of the odd multipler issues with some of the CPUS. In any case, you end up with the CPU going faster, but the ram going slower. This is one reason the FX line of CPUs were popular, because by raising the multiplier, you could get a faster CPU speed without affecting the ram speed, or alternatively, you could raise both the multiplier and the FSB speeds for to speed up both the CPU and ram.

Intel does all this differently, with its own set of rewards and difficulties when figuring out CPU and ram speeds.

I myself pretty much leave the ram alone, letting its overclocking be done through adjusting the CPU speed. I do get ram that is capable of the higher speed that occurs when overclocking the CPU, and adjusting the voltages as necessary. I've never found significant gains to be made in overclocking the ram with an AMD powered machine. Tom's has done a few articles on this and often the increase was only 1 or 2%. Overclocking the CPU by far has the greater advantage.
October 30, 2007 6:32:57 PM

I just came to the realization, why bother to choose between DDR2-1000 or 2x2GB, when you can have both!

G.Skill 4GB Dual Kit DDR2-1000 F2-8000CL5D-4GBPQ (5-5-5-15) for only 189e

I think there's my RAM :) 

Concerning the 790FX chipset, a number of manufactures (amongst them MSI and ASUS) have already leaked the details of their motherboards, despite the fact the chipset hasn't officially launched. All of them supported DDR2-1066MHz.
October 30, 2007 7:12:16 PM

Big thing with an AMD system is you want low latencies. The way the memory controller is right on chip with direct cpu access to RAM means it loves low latencies. Yes, this means improvements when running something like DDR2-800 at 4-4-4-12 timings versus DDR2-1000 at 5-6-6-18 timings. AMD loves the low latencies.

Intel on the other hand doesn't care nearly as much. There's a reason Intel chips have 4 or 6MB of L2 cache per dual-core. They use a front side bus to the northbridge memory controller. Thus, having a large L2 cache cuts down the effect of the latencies incurred on the FSB design. For this reason, it helps an Intel system more than it does an AMD system to run the ram higher with looser timings to match.

AMD's smaller caches means it needs to access main memory more than Intel does. Thus, AMD systems will feel the effect of more or less overall bandwidth more than an Intel system will, but it will also enjoy the benefits of low-latency memory much more than an Intel will.

Oh yeah, about the 4GB vs 2GB issue. I don't think that's a relevant comparison. Your getting 2GB instead of 4GB will be a different consideration. Capacity does not really dictate performance. I will agree it is harder to find 2x2GB kits with reasonable speed and timings; but I certainly have found G.SKILL 4GB (2x2GB) Dual Channel Kit DDR2-800 with 4-4-4-12 timings, or something close. Very nice kit if you ask me.

Side note: Don't tell me about Nehelam. I know. It's not here yet and so is still irrelevant to the issue. Just a note for those of you who were going to preach Nehelam to me...
October 31, 2007 4:34:18 PM

Nehalem was just a joke I threw in there, I've been considering buying a new computer since... about a year ago :lol:  I just keep saying once this thing comes out, once that thing comes out ;) 

But thanks, exactly that's the type of things I want to know :) 

One thing to note though, the absolute latency is the same:

CL 5 / 1 000 000 000 s = 5 nanoseconds

CL 4 / 800 000 000 s = 5 nanoseconds

The 1000MHz will provide higher read speeds as well, so it still seems the better choice to me, unless I can find some 800MHz RAM that has timings a nice bit below 4-4-4-12... Or is there something I'm missing here?
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