I thought 1700+ T-Bred B cpus were unlocked ONLY to 12.5x muliplier...

[ferrarifreak93]

I read in the hexus.net overclocking review that they set the muliplier to 14x on a 1700+ tbred b cpu. I thought they were unlocked only to 12.5x and that setting the multiplier higher would not work. What's the deal?

 

[KF]

The problem is really that AMD revised the multiplier system from the original 4 bits to 5 bits.

AMD CPUs do not really have a multiplier lock. The multiplier can always be reset externally. When you connect the L1 bridges, that connects some CPU pins to the internal structure of the CPU that can set the multiplier. Then you can easily set the multiplier to anything, provided the mobo has the proper stuff to do it. (otherwise you can change some other bridges to get whatever multiplier you like.) TBBs already have the L1s connected, which is convenient, but many mobos do not have everything necessary to set all five multiplier bits.

The 1700+ TBB comes set to a multiplier of 11. As a result, if your mobo can't change the 5th multiplier bit, then the multiplier will only go up to 12.5. If your mobo can change all 5 bits, then you can set all the multipliers.

Unfortunately, for old mobos there can be a further problem. The CPU puts out 4 bits of control called FID, which are sent to the chipset. Old mobos often had circuitry that intercepted and changed the FID as well as the multiplier so it would be correct, but it is the wrong FID for multipliers over 12.5. The result is that some of those high multipliers work and some don't.

To sum up, if your mobo has everything necessary, you can get all the multipliers.

 

[ferrarifreak93]

I have the abit nf7-s rev1.2 and I believe this mobo can change all 5 bits of the multiplier. Thanks

 

[ianching]

Originally posted by: ferrarifreak93
I have the abit nf7-s rev1.2 and I believe this mobo can change all 5 bits of the multiplier. Thanks

I also have the latest nForce2 board Epox 8RDA and it doesn't let me to set anything higher than 12.5x on my 1700+.

EDIT: It's a rev1.1 with latest official 3305 bios.

 

[ferrarifreak93]

Does the abit nf7-s rev1.2 change the multiplier over 12.5x?

 

[DivideBYZero]

The KG7 has an 'Over 13' setting and then you can mush up the L3's like THIS

I have just been told about this and as I have just ordered a 1700+ JIUHB I can't wait to go for 2.4Ghz!

 

[bgeh]

you never know until you try it for yourself.........

 

[FearoftheNight]

my asus a7n8x dlx can't go above 12.5...theres nothing that can be done about it?

 

[johncar]

Originally posted by: FearoftheNight
my asus a7n8x dlx can't go above 12.5...theres nothing that can be done about it?

Lots of things can be done about it, but as KF indicated they can be mobo specific and somewhat complex/need to understand AMD's Multiplier Code..
http://www.beachlink.com/candjac/index.htm link to Workarounds article...esp the sections on 1700 thru 2000 CPUs.
John C.

 

[johncar]

dupe

 

[ferrarifreak93]

woohoo! I just tried 14x and it worked perfectly! I thought I read somewhere that 1700+ chips were only unlocked to 12.5x however my NF7-S rev1.2 isn't having any trouble with higher mulitipliers.

 

[Sahakiel]

Originally posted by: FearoftheNight
my asus a7n8x dlx can't go above 12.5...theres nothing that can be done about it?

My board does it, 1001.C bios.
The thing is, the way you choose the multiplier seems to indicate the BIOS is using a hash; reading only the four bits, and if your chip has the fifth enabled, it just adds 8.

 

[FearoftheNight]

Originally posted by: Sahakiel

Originally posted by: FearoftheNight
my asus a7n8x dlx can't go above 12.5...theres nothing that can be done about it?

My board does it, 1001.C bios.
The thing is, the way you choose the multiplier seems to indicate the BIOS is using a hash; reading only the four bits, and if your chip has the fifth enabled, it just adds 8.

bah...whenever i set above 12.5 it reverts to 5 when i boot up....i'm using 1002.beta.