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What happens if I install ram that has a higher bus speed than the CPU?

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August 20, 2011 5:27:01 PM

Hello,

I'm hoping this question will be reasonably obvious to those in the know.

My old PC dates probably from around 2004.

It has an ASRock 4145GV Rev 5.01 motherboard and an Intel Celeron 2.6 Ghtz CPU. The OS is winXP Home SP3.

Now I'm up to Firefox 6, the old pensioner is not just stumbling, but falling over frequently. Once I open a few tabs, the wait can get very frustrating.

I maintain the system fairly well and have even disabled non-essential services, but the slowness is now ridiculous! Past experience suggests a memory upgrade could offer a new lease of life, especially as it currently has a pitiful 256Mb.

The motherboard has 2 slots for 184 pin ram. It claims to accept DDR1 and DDR2 up to a maximum of 2GB. Originally, I considered buying the full 2GB, but looking at the crucial website, it suggests that my useage only requires 1Gb. I reckon adding 1x 1Gb stick to the empty slot will be plenty with the existing 256Mb and if not, then I'll buy the other Gb.

The manual for the board states it will accept PC2700 (DDR333) and PC2100 (DDR266), with a caution: PC2700 is supported at FSB, 533Mhtz.

I didn't know what this was and the manual didn't say. A bit of googling reveals this is the Front Side Bus speed and is to do with the CPU. The CPU is a Northwood model with a bus speed of 400Mhtz.

I can get 1 Gb stick of PC2700 new for £15. PC2100 seems harder to find and is surprisingly more expensive - about twice as much it seems after a cursory glance and that's refurbished!

I have seen a second hand Pentium 4 (2.6Ghtz, FSB 800Htz) for £5.

What I want is to spend £15 and just clip the memory in and go. Some posts on the web suggest the memory will simply work at the speed of the FSB, some seem to suggest BIOS fiddling is required. I'm sure I could upgrade the CPU, but it's a pain and will the old fan fit or will I then find I need a new fan etc, etc.?

I expect there will be a slight performance benefit from the P4, although it's the same speed as the Celeron.

Please advise my best choice:
1. The PC2700 will work (but only at 400MHtz). £15
2. Pentium 4 is an easy upgrade to make the new memory work. (£20+ fiddling)
3. Pentium 4 will also need new fan and heatsink - Just pay for the older memory (£50+)

I'm hoping someone will assure me that option 1 is OK. If so, do I need to alter any settings such as multipliers in the BIOS after installation? Or are there any similar considerations with the other options?

Considering option 2, I looked for P4's that were faster (why not, if upgrading anyway?) and suddenly the price was £145 - perhaps these are still relatively current.

Thanks for any help.

-Tim
a b } Memory
a b à CPUs
August 20, 2011 5:50:17 PM

Option 1. But I suggest that you get 2 modules and up the system memory to 2 gb. You will be much happier with the extra memory.
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August 20, 2011 6:16:54 PM

Thanks for your reply. I assume this means it will just clip in and work. (I'm reminded of the compatibility question, so this may be a replacement rather than addition).

This system is 7 years old. I'm just surfing the net and handling documents - no 3d games, video editing or photoshopping posters - will 2Gb really make a difference?
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August 21, 2011 1:51:15 PM

So I'm just wondering if anyone else wants to chip in and offer a definitive answer.

Will PC2700 memory work with a chip that has only 400Mhtz FSB - albeit at lower than it's highest potential speed?

Any other opinions on whether 1Gb is sufficient or whether I may as well go the full 2Gb? Cost isn't really an issue - the easiest installation and best functioning system is my goal. Hassle free if that's possible in the world of computer upgrade!

While on this site, I spotted an article on HP ceasing development of webOS hardware. The Palm Pre I bought from ebay has yet to arrive and is now a white elephant, so I'm reluctant to buy something else that won't work.

Thanks for any input.

-Tim
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August 23, 2011 6:28:49 AM

Celeriac said:
So I'm just wondering if anyone else wants to chip in and offer a definitive answer.

Will PC2700 memory work with a chip that has only 400Mhtz FSB - albeit at lower than it's highest potential speed?

Any other opinions on whether 1Gb is sufficient or whether I may as well go the full 2Gb? Cost isn't really an issue - the easiest installation and best functioning system is my goal. Hassle free if that's possible in the world of computer upgrade!


I have never had or heard of issues with running ram slower than the rated speed. If you go with the pc2700 you will just have to run it at a slower speed, but i highly doubt it will cause problems.

Go the full 2gb, it will give you some extra headroom. plus mixing new and old ram may cause problems; easier just to go with all new stuff.
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