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Question on FSB overclock and RAM stability

N

Ninjaman

n00b
Joined
Oct 7, 2004
Messages
11
I recently got a Koolance EXOS water cooling system with the CPU 300 and GPU 180 blocks, and it's doing its job well. I know it's entry level and noobish, but it's my first time using liquid cooling so I thought it would be a good place to start.

Anyway, the first thing I wanted to do was try out overclocking. Now, I've read a lot of articles about Prescotts and their supposed heat problems, but to be honest I've always been very impressed with the temperatures mine has run, even with air cooling. I had a TT Polo 735 with some Arctic Silver 5 on it before and it ran 35*C idle, load about 47*C. Not too bad considering I'd just come from an Athlon XP 2100+ which ran around 55*C idle and 68*C (with an admittedly crappy heatsink/thermal paste combo). Anyway, my new temps at stock with this Koolance system are 29*C idle, 35*C load. Very nice improvement. So, after doing many overclocking experiments, I've managed the following successfully:

216 FSB, 1:1 DRAM ratio (3.44 GHz) - This yeilded excellent performance and stability, ran Prime95 torture test (blended) for over 9 hours straight with no errors, and also produced noticable gains in my games. I was pretty happy with this, but the temps didn't change at all from stock speeds so I thought I'd push it a little more.

237 FSB, 3:2 DRAM ratio (3.79 GHz) - The load temp after 10 hours of Prime95 torture test (using the in-place large FFT option) was only 41*C. I was very happy about this. However, you'll notice my DRAM ratio was pretty low for DDR400. I figured I could at least get away with a 5:4 ratio here, which was below my RAM's specs. However, anything above 3:2 and my system would barely make it to the Windows loading screen before rebooting.

That brings me to my main question - even though I set the DRAM ratio to 5:4, which runs the RAM at 189.6MHz, which is below its spec of 200 MHz, it wouldn't run until I set it even lower at a 3:2 ratio, where it ran with no issues at all. Of course, the low clock on the ram severely throttled my system performance, making the large CPU overclock fairly worthless. I'm seriously boggled by this, as the RAM performs very well overclocked by 16 MHz, yet can't even boot windows underclocked by 10.4 MHz. Is there something going on here that I'm not aware of? I don't understand why I can't keep my system stable at 3.79, since the temps are fine. As far as voltages, I've got the CPU set to 1.50 and the DRAM is only rated for 2.6 so I tried 2.65 and 2.75, both to no avail. The ram runs fine at up to 2.85 with the first overclock I mentioned. For RAM timings, I have to use 3-4-4-8 or the system won't even POST if the RAM is overclocked, though it's rated to run at 2-3-3-6 at 200 MHz. Any ideas? Sorry about the long-winded post, but I wanted to be specific. Thanks ahead of time!

Edit: for some reason my sig wasn't showing up so here are my system specs:

Pentium 4 Prescott 3.2 GHz | 1 GB PC3200 Corsair XMS RAM
eVGA GeForce 6800 GT | 2x120 GB WD SATA HDDs
Koolance EXOS Liquid Cooling | Antec TruePower 430 PSU
Soundblaster Audigy 2 ZS | Asus P4P800-E Deluxe MB
some other stuff that isn't important
 
Well, I can't do looser timings than 3-4-4-8, that's as loose as it gets. What I'm asking is, basically, is my RAM what's holding back my overclock, or does it sound like something else? I can upgrade my RAM if need be to get a 3.8 (or even higher) overclock, but I'd like to know with reasonable certainty that it's my current RAM that's the culprit.
 
i was gonna say PSU, but you have a good PSU...how old is the RAM?? you might have gotten a bad set or one bad one...

see about RMAing it maybe...but i'll post again if i can think of anything else
 
Yeah, my first reaction was PSU too. I looked into it pretty thoroughly, and finally, on another board I post on, one of the users who had basically the same system as me told me he had the same PSU and had no troubles with reboots. From what research I've done, I know that the PSU should have little trouble with the overclock I'm attempting...also, the fact that every single OC option I've tried involved tweaking the RAM setting, not the CPU VCore (with which I have a very small range of options - 1.4-1.55) or the FSB. I actually got the system to boot on 250 FSB @ 4GHz with the RAM at 3:2 3-4-4-8 but it wasn't long before a blue-screen. The temps were never higher than 41*C. I am using the Asus Probe temp reading as the Koolance LED temp seems to read a bit low (or maybe the Asus one is too high). Either way, temperature does not seem to be the issue. Unless I'm totally missing something.

Either way, the RAM is totally fine - I've run memtest86 on it for a couple hours and it checks out great, even OC'ed at 216MHz. My best guess is that running the RAM at a reduced ratio still doesn't compensate for the increased strain of the FSB overclock. Either way, I've ordered some OCZ PC3700 Gold Rev. 3 to replace it, so I guess I'll find out pretty soon. Still, I'd appreciate any input, as I'm still learning about overclocking, and frankly I'm having a good time with it.
 
isn't it fun? finally figured out that my pc wouldn't freeze at 2.4GHz, ran some aquamark3...very happy with results

44,942...still trying to break 45000

but hey, if it still doesn't go with the pc3700, then it could be mobo...but i'm 99.9% positive its RAM

anyways, enjoy that hot shit RAM...
 
Try opening up the side and blowing a fan on or near the northbridge. See if that helps any.
 
Try more voltage to the RAM. Some RAM likes more voltage. Just don't go overboard with that. ;)

I got my PC3200 RAM up to 224 FSB once. Now it doesn't want to go over 208 fsb. :(
 
Alex - thanks, that's pretty reassuring. I'll let you guys know how it goes tomorrow :)

gmkmay - I did try that, didn't do much. I powered down and touched the northbridge heatsink and it was warm to the touch but not so much that I couldn't hold my finger on it. I think it's fine, especially since it runs at 237 MHz perfectly with the RAM clocked way down.

’m‚³‚ñ - Tried every voltage setting my mobo supports, which is 2.55, 2.65, 2.75, and 2.85. The RAM is actually only rated to run at 2.6, but the weird thing is how when I was running a 1:1 ratio at 216 FSB it actually worked fine at every voltage setting. I'm getting sick of running benchmarks on this damn thing, I'm gonna give it a rest and wait till I install that OCZ stuff. Hopefully I'll be seeing some nice overclocks by then.

There is one thing I forgot to mention - when running Prime95, Asus Probe shows the core voltage drop from about 1.53 to around 1.42 or so. Is this a significant drop (Probe doesn't seem to think so, as the threshold is set to a 10% drop), and if so, what is the cause? It acts this way at stock speeds as well (usually 1.425 drops to around 1.3-something).

Thanks to all of you for your help.

UPDATE (if anyone cares): Well, it was the RAM. I put the OCZ RAM in and it's running at a 238 FSB (3.8 GHz) at a 1:1 ratio with no problems, and doesn't get a degree above 41*C. This is awesome.
 
Ninjaman said:
Sell it, hopefully. Want it?
Click to expand...

It's possible. How much you want for it? I need some cheap RAM that I can toy around with (this is going into a system that isn't used for anything but Folding@Home).
 
UPDATE (if anyone cares): Well, it was the RAM. I put the OCZ RAM in and it's running at a 238 FSB (3.8 GHz) at a 1:1 ratio with no problems, and doesn't get a degree above 41*C. This is awesome.
Click to expand...

Is this 41C degrees reported by Koolance LED or by motherboard monitor? :confused:

Also, could you please tel what is your processor "S" code? It can be found either on the top side of procesor itself or at the retail box where it says part number (close to the barcode): something like this BX80546PG3200ESL7E5. In this example SL7E5 is your "S" spec that determines the stepping.
 
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