Athlon Bus Limitation?

[Shinei]

Argh, apparently there's no edit. Way to start off a first post.

Anyway, I was thinking about the current AXP design limitations, and how people are getting around 2.3GHz on air cooling. Would it be possible to take an Athlon XP, drop the multiplier down to a 9x and widen the bus to 250MHz? Of course, you'd need some serious RAM to support that, but, well, is it possible?

Speaking of RAM, I did also want to ask what kind of companies I should be looking at for Hynix chips; I read that thread a while back about PC3200 going to DDR520 stably using Hynix chips, and that kind of overclock should be PLENTY for an AMD system, yes?

Edit: Double d'oh. Pardon me for being dumb and not RTFM'ing before posting. :s

 

[Shinei]

Double post, not your friend.

 

[DivideBYZero]

Some people have 220Mhz on air with bartons, but you need to do some serious research on components and core steppings.

To answer your initial question, you should be able to select the multiplier on your XP with most modern mobo's. I say should as some new bartons have been turning up locked, but it seems random at the moment.

Up and down are usually an option, but again this will depend on your motherboard supporting the lower multipliers.

 

[Shinei]

I'm aware of the unlocked multipliers on most modern AMD motherboards, and the recent post-week-40 multiplier locks on the 2500+ Bartons... I'm pretty sure the more expensive Bartons are still unlocked, though, since it wouldn't be in AMD's best interests to lose their entire overclocking market (which, judging from the posts around here, would be EVERYONE); like I expressed earlier in the AMD overclock castration news topic on the main page, AMD just wants to stem the hideous losses from selling chips at a $260 loss per chip (2500+ instead of 3200+), they don't want to kill overclock completely.
Also, aren't most AMD motherboards these days multiplier-enabled from 5x to 22x, with half multiplier values after 10x? That's what I've been gathering from motherboard reviews I've read here and elsewhere...

And I mentioned 2.3GHz as the "magic number" because most people bring their FSBs to 220 with an 11x multiplier for a clock of 2.4GHz, which seems to be the absolute maximum without resorting to a LN2 saturation or VapoChill solution, both of which cost more to install than the rest of the computer... 250x9 is around 2.3GHz, which should be just below the clockspeed limit and offering a bus width that should be able to at least compete with its bigger brother, the A64, and its direct competition, the P4-C. It's definitely no on-die controller, but, for a $144 processor (2800+ at NewEgg), is it really all that bad? My guess would be "no".
Of course, like I also mentioned earlier, I wanted to know about Hynix chipped RAM because DDR400 can be clocked to DDR520 according to that one overclock thread I saw... And, of course, with a 250MHz bus, you're going to need DDR500 RAM to run 1:1, plus a low latency (2-3-3-5 at the minimum, 2-2-2-5 would be best but possibly not an option at that high of an overclock) to cater to the AXP's need for tight timings and low bus speed over raw bandwidth.

(Side note: I've been reading the AT forums and articles for a while, I just recently signed up because the anonymous posting was disabled in the public topics and I finally acquired a paid email account to sign up with, so if I sound like I'm highly informed, you have only yourselves to thank for not making me look like a moron. )

 

[TerryMathews]

Most nForce2 chipsets aren't stable at a FSB that high, but you might be able to pull it off by raising the chipset voltage.

The Athlon doesn't care what bus frequency it runs at.

 

[jiffylube1024]

Originally posted by: TerryMathews
Most nForce2 chipsets aren't stable at a FSB that high, but you might be able to pull it off by raising the chipset voltage.

The Athlon doesn't care what bus frequency it runs at.

Exactly - the Northbridge gets too hot, or doesn't have enough voltage to run that high (in which case it would run even hotter), or just plain can't do that speed. 220-230 Mhz seems around the maximum current NF2 boards can do.

As for 2.3 GHz being the "sweet-spot", I'd say 2.2 is a much more "safe" estimate. If you think the majority of 2500+ chips are making it to 2.3 Ghz totally stably then someone's feeding you some bad info.

As for Hynix memory - no idea. Last I heard, memory with Winbond BH-5 chips was the best "deal" for cheap memory that will do 220 MHz and above.

 

[Jeff7181]

My early A7N8X Deluxe Rev. 2.0 is capable of running a 233 Mhz FSB. I would run it at that speed, but I can't find RAM that will run at that speed for a reasonable price... and using a RAM divider with an Athlon XP doesn't work because you don't gain that much clock speed by doing that. Before when I had PC2700 RAM I use to run the FSB at 221, the multiplier at 10, and the FSB at 75% which performed WAY better than being limited to a 166 Mhz FSB to keep the RAM in sync.

 

[Shinei]

2.2 is a more common overclock, but I've seen 2.3 with a bump from stock Vcore to 1.7 or 1.75 volts (mostly from posts in this forum, heh). It's a riskier overclock but still possible on air cooling, and since I didn't want to spring for the extra cash to get a TEC junction or a fish tank, 2.3GHz is my absolute limit.
Besides, the chip I want to abuse is a 2800+ that I just got from Best Buy (it's technically a Christmas gift, so I'm not supposed to have it yet; hasn't stopped me from asking you guys anything about it though ), which is why I was asking about the limit on Athlon architecture with air cooling. I was going to drop an SLK-700 with an Antec 80mm fan on it instead of stock, figure that should buy me a few extra megahertz on top of the silicon's capabilities... 2.2 with a 200x11 is my fallback if my experiment with 250x9 doesn't work, since 2.2 is more or less always an option, unless you get an incredibly bad overclocker.

As for the northbridge getting too hot: Have you seen that Swiftech northbridge cooler? Though even with the cooling there's always the risk of killing the silicon from the voltage... :s

Lastly: Saw some 2x 256 packages of Kingston PC3200 Value RAM in Best Buy. Rated for CAS 3 (sadly), but they seemed to have Hynix chips from what I could tell. Would those chips be stable at 2-2-2-5 clocked to DDR433?

 

[TerryMathews]

Originally posted by: Shinei
Lastly: Saw some 2x 256 packages of Kingston PC3200 Value RAM in Best Buy. Rated for CAS 3 (sadly), but they seemed to have Hynix chips from what I could tell. Would those chips be stable at 2-2-2-5 clocked to DDR433?

Let me make sure I'm completely understanding you. You want us to tell you if some RAM you saw at Best Buy that's rated for 200MHz CAS 3.0-3-3-9 (probably) is going to be stable at 216MHz CAS 2.0-2-2-5?

It's a stretch.

 

[Shinei]

Well, I imagine people have had experience with Hynix RAM, so I was asking to see if I could expect the same general performance as their results... Was worth a shot, at the least. Thanks for the opinion though, trying to see if it's a better buy to just grab some of that Kingston as a placeholder until I can scrounge enough to get Mushkin Level-II from NewEgg.

 

[Jeff7181]

Just a note... it's not heat that limits the overclock of the FSB... the chipset just can't handle speeds that high.

 

[SickBeast]

Originally posted by: Shinei
Well, I imagine people have had experience with Hynix RAM, so I was asking to see if I could expect the same general performance as their results... Was worth a shot, at the least. Thanks for the opinion though, trying to see if it's a better buy to just grab some of that Kingston as a placeholder until I can scrounge enough to get Mushkin Level-II from NewEgg.

I have two sticks of Hynix RAM...it was sold to me as Micron, but the chips are marked Hynix. The best that I have been able to do with them is 200mhz @ 8-3-3-2.5 (CAS 2.5). For some reason I haven't been able to run my FSB at more than 205mhz, even with relaxed RAM timings and an increase in voltage. I've been thinking that there is some sort of limitation within the Athlon chip itself, but I'm starting to think that it could be either my chipset getting too hot or my memory.

My CPU is a Barton 2500+, and it runs 100% stable at 2200mhz at 1.70v. It's actually very close to full stability at stock voltage at that speed...it's quite impressive. I'm guessing that I could get another 100mhz or so out of it if I bump the voltage up to 1.775 or so, but my system doesn't seem to want to run beyond 200FSB.

My chip is multiplier locked, by the way.

 

[Shinei]

Ouch, SickBeast... Guess that guy's DDR520 was just a fluke. Thanks for the information though, I'm always looking for input to help me decide on the best deal; that 2x 512 Mushkin PC3500 for $285 on NewEgg is shaping up to be the winner so far.
Always looking for more information though, so if you think my idea is terrible/impossible/whatever, feel free to reply with as much technical information as you like.

 

[MatthewF01]

Originally posted by: Jeff7181
Just a note... it's not heat that limits the overclock of the FSB... the chipset just can't handle speeds that high.

thank you.

i just read this whole freakin thread waiting for someone to state this fact as simply as done by mr jeff here.

and he [along with the other few people who casually mentioned it] is right-- the chipset isnt stable.

At some point you are going to hit a wall which will be the chipset, youll have to try bumping up the voltage on the chipset, then youre going to hit another wall. 250 is a real stretch. After the NF2 chipset got re-released as 'Ultra' and was hitting higher FSB's, the avg was like 225 or so.
And if your BIOS doesnt provide you with these voltage settings, then a voltmod should be in order.

I was told that you could determine the chipset's maximum sustainable FSB setting by doing the following:

-lower cpu mult to 8.5 or 9x or so
-set FSB to 200
-set memory ratio or percentage down to like 75%
-bump up FSB incrementally

in this scenario, neither CPU nor memory are stressed on the higher bus/clock speed, only the northbridge. This might be a start in finding the right motherboard for your quest for the holy 250x9.

 

[Acanthus]

Originally posted by: TerryMathews

Originally posted by: Shinei
Lastly: Saw some 2x 256 packages of Kingston PC3200 Value RAM in Best Buy. Rated for CAS 3 (sadly), but they seemed to have Hynix chips from what I could tell. Would those chips be stable at 2-2-2-5 clocked to DDR433?

Let me make sure I'm completely understanding you. You want us to tell you if some RAM you saw at Best Buy that's rated for 200MHz CAS 3.0-3-3-9 (probably) is going to be stable at 216MHz CAS 2.0-2-2-5?

It's a stretch.

Kingston valueram will only do 215mhz 3-4-4-8, and thats if you get lucky.