PC failing Memtest but RAM OK

[DanGent]

Got a PC here that keeps giving errors on Memtest (both Memtest86 and 86+). The sticks of RAM are fine as I've tested them in another working comp. I've also blown the slots with a can of compressed air but still the errors appear.
with a 256MB stick of RAM I get errors at memory locations: 94.5MB and 176MB
with a 512MB stick of RAM I get errors at memory locations: 53MB and 301MB
How will this affect performance on this PC? Is there anything that can be done or is it just a faulty motherboard? What may have caused this? Its one of those Iqon Tesco PCs so I'm just assuming you get what you pay for!

Much thanks,
Dan Gent

[joel_spencer]

Could be the memory controller on the motherboard (so a replacement would be needed) or perhaps the chip or gpu memory playing up. Depending on the extent of the errors it could cause anything from a few blue screen crashes to total unstability and data loss.

[Zak33]

go into BIOS and lower the ram timings.. you prolly are asking MORE of the ram than it can give.

So, for example... some ram with run CAS 2.5 but some will only run CAS3 (this is DDR example)

In the BIOS see if you can set the Ram timing to SPD (which is the safe memory timings built into the ram module to telll the motherboard what it can do)

[DanceswithUnix]

Also worth checking voltage settings for the memory. Have had similar problems in the past with a motherboard that defaulted to the wrong voltage.

[DanGent]

really really good advice there guys. didnt even think of that!
In terms of RAM timings, I remember seeing CAS2.5 but as I wasn't really paying much attention to the timings (apart from realising that the 256MB stick was slower than the motherboard). I'll have a look in the BIOS settings and set CAS to 2.5 then memtest again. What voltages should I be setting it to? I'll find out the timing I intend to set it at. Bit odd that this would be happening with the stick that came with the computer, but I only memtested it after putting in new RAM, so that might have messed up the default settings.

I'll post back with what i find,

Thanks,
Dan Gent

[jim]

When I last had problems with memtest, I just put the FSB : DRAM ratio so that the RAM was running as slowly as possible, dropped the FSB multiplier to the minimum, and loosened the timings right off - put them to 7-7-7-24 or something I think. Tested at both stock DDR2 voltage of 1.8V and Corsair's recommended 2.1V.

It still failed, turned out to be a faulty CPU despite everybody assuring me that you don't get faulty processors.

[DanGent]

Just to update. Checked out the BIOS. This is only an IQon PC from Tesco. The only controllable settings in the BIOS for voltage are for the CPU and AGP overvoltage. Got another 256MB stick of DDR from another PC that I memtested a while ago and running memtest on it now in this possible faulty PC. Its Corsair PC3200 so it should be able to support DDR400 Cas2.5 I think (all the other corsair sticks can) yet memtest shows its only running as Cas 3-3-3-8. going to leave it memtesting to see if it finds errors.

Also, the original 256MB stick out this possible faulty machine i'm going to leave memtesting in a known working machine for about 10 hours just to make sure no errors come up. Unfortunately on memtest 86+ and 86 no CAS settings or Mhz are shown. Because its such an old BIOS or a bad chipset? So not sure what speed its running at (also tried windows memory diagnostic to see if I could find this out, but not sure if this software ever says!)

[DanGent]

Just to update, I put a known working 256MB stick of Corsair in this possibly faulty PC. DDR 400 3-3-3-8 (I think, I'll write the timings up properly if more info is needed). Memtested for 8 hours OK. So I put the original 256MB stick of RAM back in this PC and memtested for 12 hours, no errors!
The reason I've been messing around with this PC is to upgrade it with an extra 512 MB stick of generic RAM. This stick has showed errors in 2 other computers I've used for testing (so is definitely faulty) yet it doesnt explain why the original 256MB stick of RAM showed errors when testing on its own!

I've got a brand new Corsair 512MB stick of RAM DDR400, so I've put this in along with the original 256MB stick of RAM and am going to leave it memtesting for 8 hours. If theres no errors I'm just going to leave it as it is and say its a success.
No idea why it was showing errors before on a 256MB stick that is fine and also another 512MB stick that is fine......

Anything major to worry about? Maybe blowing the air out of it or all the messing around taking RAM out and putting it back in has sorted it?

Thanks for all your tips guys,
Dan Gent

[jim]

Unfortunately on memtest 86+ and 86 no CAS settings or Mhz are shown. Because its such an old BIOS or a bad chipset? So not sure what speed its running at (also tried windows memory diagnostic to see if I could find this out, but not sure if this software ever says!)

Tried CPU-Z?

[jim]

Anything major to worry about? Maybe blowing the air out of it or all the messing around taking RAM out and putting it back in has sorted it?

Thanks for all your tips guys,
Dan Gent

Yeah that wouldn't surprise me. I thought I had a dodgy CPU yesterday that wouldn't POST, happened to try the same combination again later and it worked perfectly, must've been a dodgy connection... at the end of the day, if it ain't broke, don't fix.

[GoNz0]

dust can conduct, i was ready to give up on dads old pc until i cleaner it and it never burped again.

[DanGent]

good call snooty jim on CPU-Z. I use that software all the time to see what upgrades I can do without taking the PC/laptop to pieces. I'll use that next time if Memtest doesnt tell me anything (which it frequently doesnt!)
That will definitely make my life a bit easier!