Core 2 Quad and 280 watt power supply?

Nickolai999 · Apr 20, 2017

I am wondering if I could upgrade the processor in my Dell Optiplex 755 DT with a Core 2 Duo E6550 @ 2.33 GHz to a Core 2 Quad of some sort that would work with a 280 watt psu.

Here are the specifications currently:

280 watt OEM power supply
DVD-RW Drive
2GB PC2-6400 DDR2
Intel Core 2 Duo E6550 @ 2.33GHz
NVIDIA Geforce GTX 750 Ti
500 GB 7200 RPM HDD

Thanks for any help!

Math Geek · Apr 20, 2017

if the mobo supports the cpu, you should be ok. they are roughly 100w cpu's but a 750ti is rather low powered.

but you need to see what the mobo supports from dell website. they often limit what cpu's a model can support despite socket compatibility.

Darthutos · Apr 20, 2017

what is your motherboard brand and model?
if you don't know you can download cpuz (google) and under motherboard tab tell us what you see there.

you are looking at a core2 quad cpu with 65w tdp or lower (the tdp of your current cpu).
so right now in canada for example you can get the core 2 quad q8400s for 281 cad from amazon.ca (however, whoever want to use near 300 dollars to buy a 10 years cpu I'm sure I don't know.
and after all that you still need to make sure your current motherboard is compatible with the q8400s.

Math Geek · Apr 20, 2017

q8400 is a 95w cpu like all the c2q chips. not gonna find a 65w c2q as far as i know.

part of why it may not be compatible with the mobo. other reason is cause dell often restricts a mobo to only a few cpu's depending on what they are selling it to do.

a used chip is the best way to go since if you can find a new one, it'll be way more expensive than it is worth.

Emerald · Apr 20, 2017

The system shipped with Q6600 and Q6700

Nickolai999 · Apr 20, 2017

Math Geek :

On this forum: http://
I found that on the second reply he lists compatible core 2 quads and 3 of them are 65 watts as is my core 2 duo, the Intel Core 2 Quad Q9505S, Intel Core 2 Quad Q9450S, and the Intel Core 2 Quad Q9550S. Do you think these would work in my system and if so, where can i find them?

Darthutos · Apr 20, 2017

it's not q8400 I suggested I suggested q8400s which is 65tdp according to pcpartpicker. the suffix s in this case is important.

Darthutos · Apr 20, 2017

the guy that posted on the so called second reply has suggested the non s version of the cpu(s). it sounds like your mobo should support those cpus but you may need to upgrade your 280w power supply. as for where to get the cpus use pcpartpicker or ebay. those cpus are a decade old, no one will have them new unless you are really lucky and rich and just for the heck of it.

Nickolai999 · Apr 20, 2017

Emerald :

Yes, I know that but I am concerned the 60 watts the graphics card takes up might be vital for a quad core to run safely on this system.

Math Geek · Apr 20, 2017

tech sheet https://www.dell.com/downloads/global/products/optix/en/opti_755_techspecs.pdf shows the dt shipped with the q600 and 6700 as Emerald noted. it also only lists one psu for the dt model. a q6600 or q6700 should run fine on the stock psu. you can't oc it or anything like that so at stock speeds it won't hit 100w anyway.

Nickolai999 · Apr 20, 2017

Math Geek :

I was thinking a Core 2 Quad Q6700 or Q6600 (preferably the Q6700) because I am sure they are compatible with the system and the problem is that is a 30+ watt increase and the graphics card takes up nearly as much power as a Core 2 Duo so i am worried that the motherboard or power supply may die during use.

Darthutos · Apr 20, 2017

if you are willing to put in the dollars for the cpu why not buy a new psu so that at least you won't have any problem with power?

Nickolai999 · Apr 20, 2017

Darthutos :

This computer as far as I know has a special power supply that is a certain form factor so no regular power supply will work with the case.

Darthutos · Apr 20, 2017

computer retailers go out of their way to make sure the pcs are not upgradable buy the user. Every time you want to upgrade buy a new dell!
this is why diy pc building is able to survive and thrive.

King_V · Apr 20, 2017

Sometimes true, but sometimes, when they're going for small form factors or odd shape/size, they're trying to maximize space in there. Typically, they're also lower cost systems, so, I can't exactly fault the OEMs for not putting in extreme effort in engineering such cases so that standard type PS unit shape/sizes will fit.

Just a thought, not necessarily advocating this particular practice.

BFG-9000 · Apr 20, 2017

I routinely put Q6600s into old Dells with 250-305w power supplies and they work fine even when pad-modded to 1333FSB and 3.0GHz.

None of those has more than a 30w GPU though, and yours is 55w.

william p · Apr 22, 2017

Get the latest BIOS from Dell. It installs in Windows easily. This will give support for later CPUs than Dell provided when new.
Q6700 was a 95W CPU. Your MB supports 1333 fsb. You should be OK up to Q9650. You probably won't get BIOS support for the QxxxxS CPUs, and they're very expensive. The GTX750Ti is as good as it gets without a 6 pin PCIe power cable. There might be something newer that runs under 75W but I don't know what it is. The small PSU reflects the small number of drive bays and expansion slots in the DT case. The pad modded Q6700 is probably as good as it gets for these. A pad modded Q6700 is actually 3.33GHz @ 333fsb. Some of the Q6600 are B3 stepping, some G0. All Q6700 are the better G0.
But the Q9650/9550 are the usual solution.

bambiboom · Apr 23, 2017

Nickolai999 :

Nicolai999,

There are 817 Optiplex 755 results on Passmark Performance Test. the highest CPU ratings are for the Core2 Quad Q9650, 4-core @ 3.0GHz, 95W. The fastest Optiplex 755 uses a Q9650 overclocked to 3.6GHz with a CPU rating of 5456. that system is using a GTX 750Ti. For comparison, the average CPU rating of 1,095 samples of the E6550 is 1501. The average for Q9650 is 4236 with the highest rating of the Q9650 in an Optiplex 755 at the standard clock speed of 3.0GHz is 4631. It appears on Ebay that a Q9650 these days costs about $60-70. The Q9550 2.83GHz does well also, with a top CPU score of 4396. The Q9550 is also only about $25-35.

That is rated at 95W and will not be a problem for power supply. However, the Q9650 will produce more heat and it is important that the cast Aluminum CPU heatsink be changed for the one with horizontal Steel plates with Copper tubes running through. As you can see, these are not expensive- $10 or so.

With the upgrade, consider having at least 4GB of RAM so that it's possible to run Windows 7 64-bit.

Not to throw a wrench into the works, but you might consider investing the upgrade budget plus the sales value of the Optiplex 755 into a system of two generations later. Consider:

Dell Precision T3500 Workstation Xeon W3565 QC 3.20GHz / 4GB / 320GB #7269 > $90

The W3565 is 4-core @ 3.2 / 3.46GHz, hyperthreading 130W. Where the important single-thread performance- how fast the CPU is on one core - of the E6650 is 880, for the W3565 it's 1420- and that will vastly improve 3D performance. The Passmark average of 159 samples of the W3565 is 5961, but the top mark in a T3500 is 6274. The Precision T3500 is beautifully built for long running under full load and has the advantages of 24GB of DDR3-1333 RAM instead of 8GB of DDR2-667, a faster video and disk system and a 525W power supply- theT3500 was rated to use two full size 150w GPU's. With the addition of a PERC H310 RAID controller- about $50, the disk system can be converted from 3GB/s to 6GB/s which makes an SSD fully capable. In the future, the CPU can be upgraded to the X5687 4-core @ 3.6 /3.85GHz of the W3690 6-core @ 3.47 /3.73GHz so there is a quite a bit of potential left as compared to the Optiplex 755.

I bought a T3500 for $53;

Dell Precision T3500 (2011) (Original) Xeon W3530 4-core @ 2.8 /3.06GHz > 4GB (2X 2GB) DDR3-1333 ECC > GeForce 9800 GT (1GB)> WD Black 500GB
[Passmark system rating = 1963, CPU = 4482 / 2D= 609 / 3D=805 / Mem= 1409 / Disk=1048]

That system was running 1 hour out of the box and the performance as it was was not bad at all.

over a couple of week, I purchased a CPU for $60, RAM for $28, and added a GPU and drives left over from upgrading a Precision T5500, resulting in:

Dell Precision T3500 (2011) (Rev 2) Xeon X5677 4-core @ 3.46 / 3.73GHz > 12GB (6X 2GB) DDR3-1333 ECC > Quadro 4000 (2GB) > PERC 6/i + Seagate 300GB 15K SAS ST3300657SS + WD Black 500GB > 525W PSU> Windows 7 Professional 64-bit > 2X Dell 19" LCD
[Passmark system rating = 2751> CPU = 7236 / 2D= 658 / 3D=2020 / Mem= 1875 / Disk=1221]

For comparison, the highest system rating for an Optiplex 755 at standard clock speed is 2325.

That system is fully useful in 2D and 3D CAD, graphic design, and business applications. I have a PERC H310 but have not yet installed it.

Another option if the budget is larger: $250-$350 - is to consider a Dell Precision T3600 or HP z420 with the Xeon E5-1620 4-core@ 3.6/3.8GHz. Those will use 64GB of DDR3-1600 and has an SATAIII 6GB/s disk and USB 3.0.

In my view, investing in a newer workstation is a better course with more future potential than the Optiplex 755.

Cheers,

BambiBoom

HP z420 (2015) (Rev 5) > Xeon E5-1660 v2 (6-core @ 4.2GHz) / 32GB DDR3 -1866 ECC RAM / Quadro P2000 (4GB) / HP Z Turbo Drive M.2 256GB AHCI + Intel 730 480GB (9SSDSC2BP480G4R5) + Western Digital Black WD1003FZEX 1TB> Creative SB X-Fi Titanium + Logitech z2300 2.1 speakers > 600W PSU> > Windows 7 Professional 64-bit >> 2X Dell Ultrasharp U2715H (2560 X 1440)
[ Passmark Rating = 5920 > CPU= 15129 / 2D= 855 / 3D= 8945 / Mem= 2906 / Disk= 8576] [6.12.16] Single-Thread Mark = 2322 [4.20.17]

Current Project:

HP z620 > Xeon E5-1680 v2 (8-core @ 4.1Ghz) / 64GB DDR3-1866 / Quadro P2000 5GB / HP Z Turbo Drive M.2 256GB+ Intel 730 480GB + 2X Seagate Constellation ES.3 1TB.
[Passmark (Preliminary): CPU=16837 / 3D= 8716]

Nickolai999 · Apr 25, 2017

Thanks everyone! I currently have a core 2 quad q6600 in my system and it runs great!

william p · Apr 26, 2017

bambiboom :

Nickolai999 :

Nicolai999,

There are 817 Optiplex 755 results on Passmark Performance Test. the highest CPU ratings are for the Core2 Quad Q9650, 4-core @ 3.0GHz, 95W. The fastest Optiplex 755 uses a Q9650 overclocked to 3.6GHz with a CPU rating of 5456. that system is using a GTX 750Ti. For comparison, the average CPU rating of 1,095 samples of the E6550 is 1501. The average for Q9650 is 4236 with the highest rating of the Q9650 in an Optiplex 755 at the standard clock speed of 3.0GHz is 4631. It appears on Ebay that a Q9650 these days costs about $60-70. The Q9550 2.83GHz does well also, with a top CPU score of 4396. The Q9550 is also only about $25-35.

That is rated at 95W and will not be a problem for power supply. However, the Q9650 will produce more heat and it is important that the cast Aluminum CPU heatsink be changed for the one with horizontal Steel plates with Copper tubes running through. As you can see, these are not expensive- $10 or so.

With the upgrade, consider having at least 4GB of RAM so that it's possible to run Windows 7 64-bit.

Not to throw a wrench into the works, but you might consider investing the upgrade budget plus the sales value of the Optiplex 755 into a system of two generations later. Consider:

Dell Precision T3500 Workstation Xeon W3565 QC 3.20GHz / 4GB / 320GB #7269 > $90

The W3565 is 4-core @ 3.2 / 3.46GHz, hyperthreading 130W. Where the important single-thread performance- how fast the CPU is on one core - of the E6650 is 880, for the W3565 it's 1420- and that will vastly improve 3D performance. The Passmark average of 159 samples of the W3565 is 5961, but the top mark in a T3500 is 6274. The Precision T3500 is beautifully built for long running under full load and has the advantages of 24GB of DDR3-1333 RAM instead of 8GB of DDR2-667, a faster video and disk system and a 525W power supply- theT3500 was rated to use two full size 150w GPU's. With the addition of a PERC H310 RAID controller- about $50, the disk system can be converted from 3GB/s to 6GB/s which makes an SSD fully capable. In the future, the CPU can be upgraded to the X5687 4-core @ 3.6 /3.85GHz of the W3690 6-core @ 3.47 /3.73GHz so there is a quite a bit of potential left as compared to the Optiplex 755.

I bought a T3500 for $53;

Dell Precision T3500 (2011) (Original) Xeon W3530 4-core @ 2.8 /3.06GHz > 4GB (2X 2GB) DDR3-1333 ECC > GeForce 9800 GT (1GB)> WD Black 500GB
[Passmark system rating = 1963, CPU = 4482 / 2D= 609 / 3D=805 / Mem= 1409 / Disk=1048]

That system was running 1 hour out of the box and the performance as it was was not bad at all.

over a couple of week, I purchased a CPU for $60, RAM for $28, and added a GPU and drives left over from upgrading a Precision T5500, resulting in:

Dell Precision T3500 (2011) (Rev 2) Xeon X5677 4-core @ 3.46 / 3.73GHz > 12GB (6X 2GB) DDR3-1333 ECC > Quadro 4000 (2GB) > PERC 6/i + Seagate 300GB 15K SAS ST3300657SS + WD Black 500GB > 525W PSU> Windows 7 Professional 64-bit > 2X Dell 19" LCD
[Passmark system rating = 2751> CPU = 7236 / 2D= 658 / 3D=2020 / Mem= 1875 / Disk=1221]

For comparison, the highest system rating for an Optiplex 755 at standard clock speed is 2325.

That system is fully useful in 2D and 3D CAD, graphic design, and business applications. I have a PERC H310 but have not yet installed it.

Another option if the budget is larger: $250-$350 - is to consider a Dell Precision T3600 or HP z420 with the Xeon E5-1620 4-core@ 3.6/3.8GHz. Those will use 64GB of DDR3-1600 and has an SATAIII 6GB/s disk and USB 3.0.

In my view, investing in a newer workstation is a better course with more future potential than the Optiplex 755.

Cheers,

BambiBoom

HP z420 (2015) (Rev 5) > Xeon E5-1660 v2 (6-core @ 4.2GHz) / 32GB DDR3 -1866 ECC RAM / Quadro P2000 (4GB) / HP Z Turbo Drive M.2 256GB AHCI + Intel 730 480GB (9SSDSC2BP480G4R5) + Western Digital Black WD1003FZEX 1TB> Creative SB X-Fi Titanium + Logitech z2300 2.1 speakers > 600W PSU> > Windows 7 Professional 64-bit >> 2X Dell Ultrasharp U2715H (2560 X 1440)
[ Passmark Rating = 5920 > CPU= 15129 / 2D= 855 / 3D= 8945 / Mem= 2906 / Disk= 8576] [6.12.16] Single-Thread Mark = 2322 [4.20.17]

Current Project:

HP z620 > Xeon E5-1680 v2 (8-core @ 4.1Ghz) / 64GB DDR3-1866 / Quadro P2000 5GB / HP Z Turbo Drive M.2 256GB+ Intel 730 480GB + 2X Seagate Constellation ES.3 1TB.
[Passmark (Preliminary): CPU=16837 / 3D= 8716]

As usual good stuff Bambiboom. The overclocked Q9650 is very interesting. Since the CPU has a locked multiplier and the BIOS is locked, the 3.6GHz speed looks suspiciously like a pinmod to 400fsb (9X400fsb=3.600GHz). The X38 chipset in the T3400 has hidden support for 400fsb. I've never heard of it in an Optilex before.

Core 2 Quad and 280 watt power supply?

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