GDDR3: Not as good as one would think...

While felinuz and I were decoding what exactally DDR3 uses for timings I honestally got to thinking what it really is like. Often times people look too closely at the speeds and not the timings themselves... Perhaps we have overlooked what is really going on and are being taken advantage of.

Im going to list several GDDR timings to give a overall impression but I will list the DDR3 for now. Here is what your fancy card is actually using... this may come as a suprise to many:

Samsung GC20
Voltage: 2.0v and 1.8v
Speed: 1000mhz
Timings (CAS-TRP-TRCD-TRAS): 7-6-7-15

Samsung GC16
Voltage: 2.0v and 1.8v
Speed: 1200mhz
Timings (CAS-TRP-TRCD-TRAS): 8-8-9-19

Samsung GC14
Voltage: 1.8v
Speed: 1300mhz
Timings (CAS-TRP-TRCD-TRAS): 9-9-10-22

Samsung GC12
Voltage: 1.8v
Speed: 1400mhz
Timings (CAS-TRP-TRCD-TRAS): 9-10-12-25


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Perhaps people need to re-consider their feelings at Rambus's XDR...Because clearly this isnt what I would want to run on my desktop

this was no surprise to me really.
ddr3 is just a numbers gimmick imo,as is ddr2 but i could be totally in denial as i havent researched this all that much.
sure we need faster ram with higher bandwith but they are sacrificing timings for mhz wich looks nice in intel land but hasnt been even proven better than ddr1 therer either.
what we need isnt more mhz but a faster memory bus alone.
i never had an issue with rambus myself except for the part where they had to add 2 sticks at a time but im sure they are past that.

so yeh i dont see amd doing ddr2 or 3 myself if they are smart.which we all know they have been known to make not so good moves.but they have been making much better decisions in the desktop area than intel imo also.but they cant afford to make a big mistake when it concerns desktop performance.

AMD is already going DDR2, see socket m2

man_utd said:

AMD is already going DDR2, see socket m2

Click to expand...

roadmaps change faster than my udies do errr i mean

That's not surprising. This whole move to increased clockspeeds with much looser timings bothers me in general...it's just not a smart approach. It's the Pentium4 approach instead of the Dothan approach, and the Dothon has a lot more future potential.

I like the outlook of XDR much better myself also but if RAMBUS keeps it proprietary again...It'll be just like their last time out...$500 for 2x256 sticks of ram...

yeah, that's too much lol

The timings are where they should be. On my old 5900XT that died of overvolting in december of last year I tried something like this out. My friend helped me change the latencies on the memory in the bios and I ran 3dmark05. With each latency I ran the memory as fast as it would go. Trust me, the speed increase you get from increasing the latencies more than makes up for the increased latency. If you go too far though you don't gain any more speed and loose performance.

The same is true for your desktop but it has a different sweet spot. Try running a cas of 1 and see how fast you can run your memory now. If you increase the latency to 1.5 and then 2 and then 2.5 you know you can go a lot faster. Some ddr1's sweet spot is 2 and others is 3 for the most performance. But also, if I go into my bios now and change the cas latency from 2 to 3 (oops, I can't because I'm on a mac), I probably won't notice any difference whatsoever unless I start running benchmarks and noticing that it is a tiny bit slower. But if at cas2 I can get 205mhz and at cas3 I can get 280mhz, I will run cas3.

The very high memory latencies of ddr3 would not be good for your desktop, but would work best on a graphics card. For instance, my fx5900xt ran ddr1. It ran that memory to 550Mhz, almost twice as fast as any desktop memory you can buy. It ran very high latencies though. I think the stock bios was cas4 and the bios I used for 550Mhz cas5. Cas5 proved to be the best for performance due to overclock headroom. (the 550Mhz was reached before volt modding though) This was ddr1, the same type sitting in most people's desktops but at higher latencies and much higher speeds. If you set the cas to 5 in your comp, it would be nearly unusuable. If you set cas2 or 1.5 in your ddr1 memory videocard, the same holds true.

Just comes back to whats better, tighter timings or more mhz

i know myself and others got some great results from lowering our clocks on our x850xts memory and tightening up the timmings a bit. with 50mhz less clock and better timmings i pulled in a couple hundred points more on 3dmark03.

for what its worth i think ddr2 is the sux. i had a couple diffrent kits and found that running it over 1:1 ratio did absolutely nothing aside from make synthetic memory benchs score higher ive asked alot of people who ive noticed are using ddr2 and they pretty much all say the same thing. i guess if your going for the e-penis thing the faster memory would be great but real world benefits just arent there (from what ive found. im still waiting for someone to show me diffrently though)